Re: Using qr// with substitution and group-interpolation in thesubstitution part

[gordonfish]

On 10/25/23 10:32, Josef Wolf wrote:

[...]


Basically, I want to do the same as


   $data =~ s/^foo (whatever) bar$/bar $1 baz/mg;


but with a different interface (because it has to be embedded into a bigger
project), So I have come with this;


   sub substitute_lines {
   my ($contents, $regex, $subst) = @_;
   $contents =~ s/$regex/$subst/mg;
   return $contents;
   }
   }

   _lines ($data, qr/^foo (whatever) bar$/mg, 'bar $1 baz');


Which (mostly) works as expected. Unfortunately, this won't interpolate the
matched group $1.

[...]

You could so something like:

use feature qw(signatures);

sub substitute_lines($contents, $regex, $subst) {
$contents =~ s/$regex/$subst->()/emgr;
}

...

substitute_lines
$data,
qr/^foo (whatever) bar$/,
sub { "bar $1 baz" };


This will pass an anonymous sub routine which will be called from s/// 
replacement side thanks to the /e modifier that allows code to be 
executed there.


Also of some note is that the /r modifier is used so that s/// returns 
the resulting string instead of modifying $contents, and being the last 
statement, said resulting string is the return value.


--
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Re: Using qr// with substitution and group-interpolation in the substitution part

[Octavian Rasnita]

Hello,

I tried to find a solution that doesn't use eval, although if '$1' is sent 
as a parameter to the subroutine as a simple string, I think it either need 
to be eval'ed or replaced literally.

I made this solution to work with more capturing parans if necessary:

use strict;
use warnings;

my $data = "foo whatever bar";
$data = substitute_lines( $data, qr/^foo (whatever) bar$/, 'bar $1 baz');
print "$data\n";

$data = "foo whatever bar whatever2 baz";
$data = substitute_lines( $data, qr/^foo (whatever) bar (whatever2) baz$/, 
'bar $2 baz $1 foo');

print "$data\n";

sub substitute_lines {
   my ($contents, $regex, $subst) = @_;
   $contents =~ s/$regex(?{ $contents =~ s[$regex][$subst]gm; my @c = 
@{^CAPTURE}; $contents =~ s[\$$_][$c[$_-1]] for 1 .. @c })/$contents/;

   return $contents;
}

It prints:
bar whatever baz
bar whatever2 baz whatever foo

However, the regex above uses code interpretation in regex, which is another 
kind of eval.
So the following subroutine does the same thing with a simple replacement, 
without code interpretation:


sub substitute_lines {
   my ($contents, $regex, $subst) = @_;
   $contents =~ s/$regex/$subst/gm;
   my @matches = @{^CAPTURE};
   $contents =~ s/\$$_/$matches[$_-1]/g for 1 .. @matches;
   return $contents;
}

- Original Message - 
From: "Claude Brown via beginners" 
To: "Levi Elias Nystad-Johansen" ; "Andrew 
Solomon" 

Cc: "Josef Wolf" ; 
Sent: Thursday, October 26, 2023 12:07 AM
Subject: RE: Using qr// with substitution and group-interpolation in the 
substitution part




Josef,

Inspired by Levi's “eval” idea, here is my solution:

sub substitute_lines {
   my ($contents, $regex, $subst) = @_;
   eval "\$contents =~ s/$regex/$subst/g";
   return $contents;
}

$data = "foo whatever bar";
$data = _lines($data, qr/^foo (whatever) bar$/m, 'bar $1 baz');
print "$data\n";

The differences:
- escaped the "$" so the eval gets a literal "$contents"
- didn't escape "$" so the eval receives the value of $regex and $subst
- moved the "g" into the sub as it has no meaning for a qr//
- removed the "m" from the sub as it best left with the original qr//
- added "$data = ..." to get back the value from the subroutine

Cheers,

Claude.





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RE: Using qr// with substitution and group-interpolation in the substitution part

[Claude Brown via beginners]

I should add that if the script reads values of $regex or $subst from an 
external source, then my use of eval is seriously flawed.  For example, that 
external source might provide this value for $subst:

/; system("do-bad-things"); qr/x/

The eval will execute the "do-bad-things" command on your system.  


-Original Message-
From: Claude Brown via beginners  
Sent: Thursday, October 26, 2023 8:07 AM
To: Levi Elias Nystad-Johansen ; Andrew Solomon 

Cc: Josef Wolf ; beginners@perl.org
Subject: RE: Using qr// with substitution and group-interpolation in the 
substitution part

CAUTION: This email originated from outside of the organization. Do not click 
links or open attachments unless you recognize the sender and know the content 
is safe.

Josef,

Inspired by Levi's “eval” idea, here is my solution:

sub substitute_lines {
my ($contents, $regex, $subst) = @_;
eval "\$contents =~ s/$regex/$subst/g";
return $contents;
}

$data = "foo whatever bar";
$data = _lines($data, qr/^foo (whatever) bar$/m, 'bar $1 baz');
print "$data\n";

The differences:
- escaped the "$" so the eval gets a literal "$contents"
- didn't escape "$" so the eval receives the value of $regex and $subst
- moved the "g" into the sub as it has no meaning for a qr//
- removed the "m" from the sub as it best left with the original qr//
- added "$data = ..." to get back the value from the subroutine

Cheers,

Claude.

RE: Using qr// with substitution and group-interpolation in the substitution part

[Claude Brown via beginners]

Josef,

Inspired by Levi's “eval” idea, here is my solution:

sub substitute_lines {
my ($contents, $regex, $subst) = @_;
eval "\$contents =~ s/$regex/$subst/g";
return $contents;
}

$data = "foo whatever bar";
$data = _lines($data, qr/^foo (whatever) bar$/m, 'bar $1 baz');
print "$data\n";

The differences:
- escaped the "$" so the eval gets a literal "$contents"
- didn't escape "$" so the eval receives the value of $regex and $subst
- moved the "g" into the sub as it has no meaning for a qr//
- removed the "m" from the sub as it best left with the original qr//
- added "$data = ..." to get back the value from the subroutine

Cheers,

Claude.

Re: Using qr// with substitution and group-interpolation in the substitution part

[Andrew Solomon]

That's a fun question, Josef!

I don't think you can pass a replacement phrase around, so this is all I
came up with:

sub substitute_lines {
  my ($contents, $subst) = @_;
  $contents = $subst->($contents);
  return $contents;
}

my $data = "foo whatever bar";
print(substitute_lines($data, sub { $_[0] =~ s/^foo (whatever) bar$/bar $1
baz/mgr } ));


I'd be very pleased if someone could come up with a more elegant solution.


On Wed, Oct 25, 2023 at 6:34 PM Josef Wolf  wrote:

> Hallo all,
>
> maybe this is not exactly a beginner question, but I could not find an
> appropriate mailing list (all other lists seem to be developer realted).
>
>
> Basically, I want to do the same as
>
>
>   $data =~ s/^foo (whatever) bar$/bar $1 baz/mg;
>
>
> but with a different interface (because it has to be embedded into a bigger
> project), So I have come with this;
>
>
>   sub substitute_lines {
>   my ($contents, $regex, $subst) = @_;
>   $contents =~ s/$regex/$subst/mg;
>   return $contents;
>   }
>   }
>
>   _lines ($data, qr/^foo (whatever) bar$/mg, 'bar $1 baz');
>
>
> Which (mostly) works as expected. Unfortunately, this won't interpolate the
> matched group $1.
>
> Experiments which also do not work:
>
>
>   _lines ($data, qr/^foo (whatever) bar$/mg, "bar $1 baz");
>   # obviously, $1 is interpolated _before_ re-match is done
>
>
>   _lines ($data, qr/^foo (whatever) bar$/mge, '"bar $1 baz"');
>   # /e modifier not accepted
>
> Any hints?
>
> --
> Josef Wolf
> j...@raven.inka.de
>
> --
> To unsubscribe, e-mail: beginners-unsubscr...@perl.org
> For additional commands, e-mail: beginners-h...@perl.org
> http://learn.perl.org/
>
>
>

Using qr// with substitution and group-interpolation in the substitution part

[Josef Wolf]

Hallo all,

maybe this is not exactly a beginner question, but I could not find an
appropriate mailing list (all other lists seem to be developer realted).


Basically, I want to do the same as


  $data =~ s/^foo (whatever) bar$/bar $1 baz/mg;


but with a different interface (because it has to be embedded into a bigger
project), So I have come with this;


  sub substitute_lines {
  my ($contents, $regex, $subst) = @_;
  $contents =~ s/$regex/$subst/mg;
  return $contents;
  }
  }

  _lines ($data, qr/^foo (whatever) bar$/mg, 'bar $1 baz');


Which (mostly) works as expected. Unfortunately, this won't interpolate the
matched group $1.

Experiments which also do not work:


  _lines ($data, qr/^foo (whatever) bar$/mg, "bar $1 baz");
  # obviously, $1 is interpolated _before_ re-match is done


  _lines ($data, qr/^foo (whatever) bar$/mge, '"bar $1 baz"');
  # /e modifier not accepted

Any hints?

-- 
Josef Wolf
j...@raven.inka.de

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Re: interpolation without double quotes

[Shlomi Fish]

On Thu, 5 Jul 2018 09:58:52 -0500
p...@reason.net wrote:

> Many thanks to Shlomi and Uri: as always, you’ve greatly boosted my
> understanding of Perl! — Rick
> 

You're welcome.


-- 
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http://is.gd/htwEXQ - Integrating GNU Guile into GNU coreutils

Mephiqoleth: THERE ARE JEWS OF MANY SPECIES.
Selina: Really? That’s great - can I have a Jewish lady-cat? I want one
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Re: interpolation without double quotes

[perl]

Many thanks to Shlomi and Uri: as always, you’ve greatly boosted my 
understanding of Perl! — Rick


> On Jul 4, 2018, at 9:35 AM, Shlomi Fish  wrote:
> 
> Hi Rick,
> 
> On Wed, 4 Jul 2018 09:16:19 -0500
> Rick T  wrote:
> 
>> The following line works, even though I forgot to double quote the variable.
>> 
>> my $student_directory =  '/data/students/' . $student_id;
>> 
> 
> see http://perl-begin.org/tutorials/bad-elements/#vars_in_quotes . Perl often
> stringifies expressions even outside interpolation, such as when being
> string-concatenated.
> 
>> When I noticed this, I thought this was convenient: perl is trying to “do the
>> right thing.” But I worry that leaving them out may be bad coding practice;
>> if so, or you see other worthwhile improvements, please let me know.
>> 
>> More importantly, I wonder how perl knows to do this. Perhaps  context
>> provided by the assignment operator or the concatenation operator? If there
>> is a general rule on this, it would help me to know more widely when I can
>> omit double quotes.
>> 
>> Thanks!
>> 
>> Rick Triplett
> 
> 
> -- 
> -
> Shlomi Fish   http://www.shlomifish.org/
> First stop for Perl beginners - http://perl-begin.org/
> 
> After all is said and done, a hell of a lot more is said than done.
>— Unclear source, via fortune-mod.
> 
> Please reply to list if it's a mailing list post - http://shlom.in/reply .
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> 
> 
> 

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Re: interpolation without double quotes

[Shlomi Fish]

Hi Rick,

On Wed, 4 Jul 2018 09:16:19 -0500
Rick T  wrote:

> The following line works, even though I forgot to double quote the variable.
> 
> my $student_directory =  '/data/students/' . $student_id;
> 

see http://perl-begin.org/tutorials/bad-elements/#vars_in_quotes . Perl often
stringifies expressions even outside interpolation, such as when being
string-concatenated.

> When I noticed this, I thought this was convenient: perl is trying to “do the
> right thing.” But I worry that leaving them out may be bad coding practice;
> if so, or you see other worthwhile improvements, please let me know.
> 
> More importantly, I wonder how perl knows to do this. Perhaps  context
> provided by the assignment operator or the concatenation operator? If there
> is a general rule on this, it would help me to know more widely when I can
> omit double quotes.
> 
> Thanks!
> 
> Rick Triplett


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-
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First stop for Perl beginners - http://perl-begin.org/

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Re: interpolation without double quotes

[Uri Guttman]

On 07/04/2018 10:16 AM, Rick T wrote:
The following line works, even though I forgot to double quote the 
variable.


my $student_directory =  '/data/students/' . $student_id;

When I noticed this, I thought this was convenient: perl is trying to 
“do the right thing.” But I worry that leaving them out may be bad 
coding practice; if so, or you see other worthwhile improvements, 
please let me know.


you don't need quotes on single scalar variables. in fact it is bad 
practice and can lead to bugs when you do that. what you did is not 
interpolation but ordinary concatenation with the . operator. 
interpolation is replacing scalars (and array) variables with their 
values inside double quotes.


More importantly, I wonder how perl knows to do this. Perhaps context 
provided by the assignment operator or the concatenation operator? If 
there is a general rule on this, it would help me to know more widely 
when I can omit double quotes.


the dot operator provides string context to both its arguments. if you 
are always double quoting single scalars, you should stop it as it is 
also slower due to the extra copying of the string value.


that line is better written as:

my $student_directory =  "/data/students/$student_id";

i avoid using . when i can. it just reads better when you have the whole 
string in double quotes and you skip all the extra quote chars and . 
operators.


uri

interpolation without double quotes

[Rick T]

The following line works, even though I forgot to double quote the variable.

my $student_directory =  '/data/students/' . $student_id;

When I noticed this, I thought this was convenient: perl is trying to “do the 
right thing.” But I worry that leaving them out may be bad coding practice; if 
so, or you see other worthwhile improvements, please let me know.

More importantly, I wonder how perl knows to do this. Perhaps  context provided 
by the assignment operator or the concatenation operator? If there is a general 
rule on this, it would help me to know more widely when I can omit double 
quotes.

Thanks!

Rick Triplett

Re: Interpolation Problem

[David Mertens]

To second what Uri mentioned already,

On Fri, Jul 15, 2016 at 11:42 PM, AC P  wrote:

> 
>
> Argument "$command" isn't numeric in subtraction (-) at then it gives me
> my directory.
>
> 
>

This error message (I suspect it was a warning, can you check?) probably
reported a line number. Could you post the code in the vicinity of that
line number? (Better yet, post your whole script, or enough of a script to
reproduce the problem.)

Thanks!
David

-- 
 "Debugging is twice as hard as writing the code in the first place.
  Therefore, if you write the code as cleverly as possible, you are,
  by definition, not smart enough to debug it." -- Brian Kernighan

Re: Interpolation Problem

[Uri Guttman]

On 07/15/2016 11:42 PM, AC P wrote:

Hello Perl gurus,

I'm hoping someone here can provide a solution since I'm stuck.

I'm trying to send TL1 commands resembling "RTRV-ALM-ALL;" (the 
simplest command you can send as an example here) via Net::SSH::Expect 
but they keep getting interpolated before even reaching the TL1 device.


i think you misunderstand what interpolation means. in perl a scalar in 
a string is interpolated to its value.


I predictably receive:

Argument "$command" isn't numeric in subtraction (-) at then it gives 
me my directory.
that feels like you are quoting $command and it is NOT being 
interpolated before it gets sent to the TL1.


I think the solution lies in sending unicode e.g. chr(073) for ";" and 
chr(055) for "-" both of which are required to send the command and 
tell the TL1 device to process it.
those aren't unicode chars (well they are but they are in the first 8 
bit set so they are just ascii).


why don't you post some of the code as it is hard to tell what you are 
actually doing wrong with just your conjectures.


thanx,

uri



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Interpolation Problem

[AC P]

Hello Perl gurus,

I'm hoping someone here can provide a solution since I'm stuck.

I'm trying to send TL1 commands resembling "RTRV-ALM-ALL;" (the simplest
command you can send as an example here) via Net::SSH::Expect but they keep
getting interpolated before even reaching the TL1 device.

I predictably receive:

Argument "$command" isn't numeric in subtraction (-) at then it gives me my
directory.

I think the solution lies in sending unicode e.g. chr(073) for ";" and
chr(055) for "-" both of which are required to send the command and tell
the TL1 device to process it.

Suggestions, anyone?

Amanda

interpolation problem in emacspipe.pl script from emacswiki

[Gabriel Striewe]

Dear List,

i found on the emacswiki the following script written in Perl which is
supposed to make emacsclient read from a pipe:

#! /usr/bin/perl

# This script uses emacsclient, be sure to have a running server session.
# A server-session can be started by M-x server-start.

my $status = system(emacsclient -n --eval '(progn (pop-to-buffer 
(get-buffer-create \*piped*\)))');
if($status!=0){ exit 1; }
while(STDIN){ 
 system(emacsclient -n --eval '(with-current-buffer \*piped*\ (insert 
\ . $_ . \))');
}


Now when this script reads a list of emailaddresses for example from
mutt:

From: John Test john @test.org
From: William Testtwo william test...@test.test.org

it gives the following output:

#buffer *piped*
*ERROR*: Symbol's value as variable is void: William

everything works normaly if before feeding the output to emacspipe.pl, 
i run it through sed s/\//g, whereby deleting the double quotes.

There must be something about the interpolation. Maybe somebody has an
idea? I am not an expert at this.

Gabriel 

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Re: interpolation problem in emacspipe.pl script from emacswiki

[Uri Guttman]

 GS == Gabriel Striewe li...@gabriel-striewe.de writes:

  GS my $status = system(emacsclient -n --eval '(progn (pop-to-buffer 
(get-buffer-create \*piped*\)))');
  GS if($status!=0){ exit 1; }
  GS while(STDIN){ 
  GS  system(emacsclient -n --eval '(with-current-buffer \*piped*\ 
(insert \ . $_ . \))');
  GS }

a first pass is for you to learn the qq{} alternate quote
operator. escaping  like you do is noisy and tricky. learn about these
in perlop. qq{} is like  but you can put  inside without
escaping. you can use any delimiter you like but paired {} is among the
best (you can even have nested {} inside without escaping!). so those
lines would look like (untested):

my $status = system( qq{emacsclient -n --eval
'(progn (pop-to-buffer (get-buffer-create *piped*)))'
});

system( qq{ emacsclient -n --eval
'(with-current-buffer *piped* (insert $_))'
});

notice how much easier they are to read and you can see the  are for
emacs lisp and not for perl.

actually i just noticed the first one doesn't to any perl interpolation
so that could use q{} which is like ''. the second one needs double
quotish behavior since it interpolates $_.

another improvement would be to use a named variable in the while which
makes the code easier to read. i stay away from $_ unless it is required
or it has a major win. neither case applies here, so this is
better. also you don't chomp the input line and that may also screw
things up:


while( my $email = STDIN ) { 
chomp $email ;
system( qq{ emacsclient -n --eval
'(with-current-buffer *piped* (insert $email))'
});
}

better formatting helps too. that code is now ready for you and others
to understand easily and maintain.

uri

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interpolation techniques (was Re: Here Docs)

[Uri Guttman]

 t == trapd00r  trapd...@trapd00r.se writes:

   i would say to just use a temporary scalar variable. there is no shame
   in doing this and it is simpler than using the Interpolation module
   which is doing tied things and calling eval (which is dangerous).

  t When I dont want to use a temp var, I usually do like this:

  t print  EOF;
  t   foo @{[scalar(localtime)]} bar
  t EOF

  t Do you approve? I do not see the benefit of using that Interpolation
  t module.

that technique is old and not well liked by many. i never use it. it is
just too noisy for my taste. also you can do a scalar version with
${\EXPR} but it also supplies a list context so there is little benefit
over the array version.

if you are just putting in a couple of elements then temp vars are fine
and very clear. 

in a boston.pm thread on the same subject, the OP wrote his own
version of the Interpolate module including the tied object and
eval. that is just plain overkill.

check out these methods i listed in that thread:

**

first off there are the old hackish ways of doing this with
dereferencing anon refs with code inside:

text${\$foo-method()}more text
t...@{[$foo-method()]}more text

note that in both cases the method (or sub) is called in list
context. this style is frowned upon for production code as it is noisy
and not easy to read.

an old reliable way is using sprintf as long as you don't have too many
fields which again makes it noisy.

sprintf text%smore text, $foo-method() ;

if you want more templating without all the eval fuss and tied stuff,
try my module Template::Simple. it would be very easy to use this for
method interpolation:

use Template::Simple ;

my $tmpl = Template::Simple-new() ;

my $out = render( text[%STUFF%]more text,
{ STUFF = $foo-method() } ) ;

so no eval or tied is ever needed for basic stuff like interpolating
methods and subs.


three more ways i forgot to add. there is no shame or anything wrong with
first putting the value of a method or sub call into a scalar and
interpolating that.

my $val = $foo-method() ;
my $out = text${val}more text ;

since you can interpolate hash values, a simple templater can be done
this way:

my %vals = ( FOO = $foo-method(), BAR = $bar-other_method ) ;
my $out = text$vals{FOO}more text$vals{BAR} ;

and the old way of using . is still fine even if i don't like it:

my $out = text . $foo-method() . more text ;

i just hate using . by itself. hard to read and rarely needed. note that
i use .= a ton of times which is not the same. :)

so that is 6 ways to do it without eval and tied. :)



the point is choose a way to do it with the least work, least pain and
most clarity for the reader of your code. the interpolate module (and
copies) is dangerous because of its use of eval and slow (tied objects,
tons of code to do something simple).

uri

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Late interpolation of a scalar variable inside a string

[Chap Harrison]

I want to compute a file pathname based on a template at runtime,  
when I know the value of a variable that the template uses.


In other words, the template for the path name looks like this...

/foo/bar/$project/here

...and I want to evaluate this expression once I have set the value of  
$project.


Here's what I've got:

#!/usr/bin/perl
use strict;
use warnings;

my $project = my-project;
my $all_projects_path = '/foo/bar/$project/here';
my $project_path;
my $temp = '$project_path  = $all_projects_path';

print \$project is: $project\n;
print \$all_projects_path is: $all_projects_path\n;
print Evaluating: $temp\n;
eval $temp;
print \$project_path is now: $project_path\n;

-

Output:

$ doit
$project is: my-project
$all_projects_path is: /foo/bar/$project/here
Evaluating: $project_path  = $all_projects_path
$project_path is now: /foo/bar/$project/here

-

The variable $project wasn't interpolated.
I've read perldoc on 'eval', and googled a bit, but no joy.
I know this is going to be a forehead-slapper, but what have I done  
wrong?


Thank,
Chap

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Re: Late interpolation of a scalar variable inside a string

[Chas. Owens]

On Sat, Mar 14, 2009 at 18:04, Chap Harrison c...@pobox.com wrote:
 I want to compute a file pathname based on a template at runtime, when I
 know the value of a variable that the template uses.

 In other words, the template for the path name looks like this...

 /foo/bar/$project/here
snip
 I've read perldoc on 'eval', and googled a bit, but no joy.
snip

String eval is bad mojo.  What you really need is either a template
module* (if your needs are very complex) or a simple substitution (if
you needs are simple).

#!/usr/bin/perl

use strict;
use warnings;

my $project_path_template = /foo/bar/{PROJECT}/here;

for my $project (qw/project1 project2 project3/) {
(my $project_path = $project_path_template) =~ s/\{PROJECT\}/$project/;
print the project path is $project_path\n;
}

* Search CPAN for template modules until you find one with the
features you want, this one looks fairly close to what you want:
http://search.cpan.org/dist/Text-Template/lib/Text/Template.pm

-- 
Chas. Owens
wonkden.net
The most important skill a programmer can have is the ability to read.

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Re: Late interpolation of a scalar variable inside a string

[John W. Krahn]

Chap Harrison wrote:
I want to compute a file pathname based on a template at runtime, when 
I know the value of a variable that the template uses.


In other words, the template for the path name looks like this...

/foo/bar/$project/here

...and I want to evaluate this expression once I have set the value of 
$project.


Here's what I've got:

#!/usr/bin/perl
use strict;
use warnings;

my $project = my-project;
my $all_projects_path = '/foo/bar/$project/here';
my $project_path;
my $temp = '$project_path  = $all_projects_path';

print \$project is: $project\n;
print \$all_projects_path is: $all_projects_path\n;
print Evaluating: $temp\n;
eval $temp;
print \$project_path is now: $project_path\n;

-

Output:

$ doit
$project is: my-project
$all_projects_path is: /foo/bar/$project/here
Evaluating: $project_path  = $all_projects_path
$project_path is now: /foo/bar/$project/here

-

The variable $project wasn't interpolated.
I've read perldoc on 'eval', and googled a bit, but no joy.
I know this is going to be a forehead-slapper, but what have I done wrong?


Why not use sprintf() and '/foo/bar/%s/here' as the template:

my $project = my-project;
my $all_projects_path = '/foo/bar/%s/here';
my $project_path = sprintf $all_projects_path, $project;




John
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Re: Late interpolation of a scalar variable inside a string

[Chap Harrison]

On Mar 14, 2009, at 5:24 PM, John W. Krahn wrote:


Why not use sprintf() and '/foo/bar/%s/here' as the template:


On Mar 14, 2009, at 5:19 PM, Chas. Owens wrote:


* Search CPAN for template modules until you find one with the
features you want, this one looks fairly close to what you want:
http://search.cpan.org/dist/Text-Template/lib/Text/Template.pm



Thank you both.  Good to know about Template.pm.  Also good to know  
the eval method was inadvisable.  Since my needs are so simple, I went  
with the sprintf solution - simplest of all.


Chap

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Re: Stopping variable interpolation/evaluation

[pushkar . naik]

 Use print(), not printf().

 --
 Gunnar Hjalmarsson
 Email:http://www.gunnar.cc/cgi-bin/contact.pl- Hide quoted text -

 - Show quoted text -

Thanx Gunnar and Octavian, print() and chomp() together did the job
just fine.
~Pushkar


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Re: Stopping variable interpolation/evaluation

[Octavian Râsnita]

From: pushkar.n...@gmail.com

Hi,  I have a line read in perl from a file that itself is a source
code for languages like c/sv etc. The variable containing this line
contains special characters like %d. When i print this line to another
file, the %d is evaluated and a 0 is getting printed. How do i
overcome this and tell perl to strictly not interpolate/evaluate any
contents of this variable and simply print it as is !
~Pushkar

open RFH  File1.txt;


Better use:

open(my $rfh, , file1.txt) or die Can't read file1.txt - $!;


open WFH  File2.txt;


Better use:

open(my $wfh, , file2.txt) or die Can't write to file2.txt - $!;


while ($line = RFH)


Better use:

while (my $line = $rfh) {


 chop($line);


You might want to use:

chomp $line;


 printf WFH $line\n;


You might want to use:

print $wfh $line\n;

Octavian


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Stopping variable interpolation/evaluation

[pushkar . naik]

Hi,  I have a line read in perl from a file that itself is a source
code for languages like c/sv etc. The variable containing this line
contains special characters like %d. When i print this line to another
file, the %d is evaluated and a 0 is getting printed. How do i
overcome this and tell perl to strictly not interpolate/evaluate any
contents of this variable and simply print it as is !
~Pushkar

open RFH  File1.txt;
open WFH  File2.txt;

while ($line = RFH)
{
  chop($line);
  printf WFH $line\n;
}

File1.txt :
ovm_report_info(DBG_INFO, $psprintf(Programming Bank %d Reg %d, (i/
32), l_uint_reg_num), OVM_HIGH);

File2.txt
ovm_report_info(DBG_INFO, $psprintf(Programming Bank 0 Reg 0, (i/
32), l_uint_reg_num), OVM_HIGH);


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Re: Stopping variable interpolation/evaluation

[Gunnar Hjalmarsson]

pushkar.n...@gmail.com wrote:

Hi,  I have a line read in perl from a file that itself is a source
code for languages like c/sv etc. The variable containing this line
contains special characters like %d. When i print this line to another
file, the %d is evaluated and a 0 is getting printed. How do i
overcome this and tell perl to strictly not interpolate/evaluate any
contents of this variable and simply print it as is !
~Pushkar

open RFH  File1.txt;
open WFH  File2.txt;

while ($line = RFH)
{
  chop($line);
  printf WFH $line\n;

^^

Use print(), not printf().

--
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Email: http://www.gunnar.cc/cgi-bin/contact.pl

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Re: interpolation of function reference in a here doc

[Brad Baxter]

On Jul 2, 9:27 am, [EMAIL PROTECTED] (Rob Dixon) wrote:
 Gabriel Striewe wrote:
  What do I do wrong?

 First of all, the ampersand subroutine designation is outdated and dangerous
 and it is far better to use the indirect notation for a subroutine call:

 $hello-()

 Perl will interpolate only simple variables or array or hash elements
 or slices. However we can cheat by putting the result of the call into
 an anonymous array and then dereferencing it:

 print END;
 hello @{[$hello-()]}
 END

And don't worry too much about simply using a string:

my $msg = $hello-();
print END;
hello $msg
END

--
Brad


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Re: interpolation of function reference in a here doc

[jenda]

You may want to have a look at Interpolation.pm from CPAN.

Jenda
== [EMAIL PROTECTED] == http://Jenda.Krynicky.cz ==
: What do people think?
What, do people think?  :-)
 -- Larry Wall in [EMAIL PROTECTED]


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Re: interpolation of function reference in a here doc

[Adriano Ferreira]

On 7/2/07, Gabriel Striewe [EMAIL PROTECTED] wrote:

Dear List,

I wanted to interpolate a function reference in a here doc.
The following works fine:

my $hello = sub {
 return hello world!;
};

printf hello $s\n, $hello();

But when I use a heredoc instead, it doesn't work:

print END;
hello $hello()
END

At least it does not properly dereference this function
reference.

What do I do wrong?


You will encounter the problem if instead of

   printf hello %s\n, $hello();

you would have tried:

   print hello $hello()\n;

That's an issue with the rules of string interpolation. (Read perldoc
perlop, section on quote-like operators.) Simplistically, I think the
right thing you are expecting for (calling the code ref in $hello) is
not done because the only sigils that matter in interpolation are $
and @. That's why

  $ perl -e '$h = sub {1}; print hello $h() '
  hello CODE(0x10240d64)()

(where the only thing interpolated was the stringification of the code
ref in $h).

The weird/scary way to make it work is

$ perl -e '$h = sub {1}; print hello @{[ $h() ]} '
hello 1



Thanks for your advice.

Gabriel

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Re: interpolation of function reference in a here doc

[Xavier Noria]

On Jul 2, 2007, at 2:46 PM, Gabriel Striewe wrote:


Dear List,

I wanted to interpolate a function reference in a here doc.
The following works fine:

my $hello = sub {
 return hello world!;
};

printf hello $s\n, $hello();


In Perl printf is rarely used because double-quote strings allow  
interpolation of scalars and arrays, and because print accepts an  
arbitrary number of arguments.


Interpolation does not understand function calls, though, so you  
either use a multi-argument call like this:


  print hello , $hello-(), \n;

or either use this hack:

  print hello @{[ $hello-() ]}\n;

Here-documents have double-quote semantics unless you put single  
quotes around the terminating string, so that last trick works in  
here-documents as well.


-- fxn


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Re: interpolation of function reference in a here doc

[Rob Dixon]

Gabriel Striewe wrote:


I wanted to interpolate a function reference in a here doc.
The following works fine:

my $hello = sub {
 return hello world!;
};

printf hello $s\n, $hello();

But when I use a heredoc instead, it doesn't work:

print END;
hello $hello()
END

At least it does not properly dereference this function
reference.

What do I do wrong?


First of all, the ampersand subroutine designation is outdated and dangerous
and it is far better to use the indirect notation for a subroutine call:

$hello-()

Perl will interpolate only simple variables or array or hash elements
or slices. However we can cheat by putting the result of the call into
an anonymous array and then dereferencing it:

print END;
hello @{[$hello-()]}
END


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Re: Interpolation of backslash-escapes

[Randal L. Schwartz]

 Rob == Rob Dixon [EMAIL PROTECTED] writes:
 Can anybody think of an elegant solution?

Rob eval qq($val);

s/elegant/hacky, dangerous, broken/

Consider $val = ), $yourcode_here, (.

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Re: Interpolation of backslash-escapes

[Rob Dixon]

Randal L. Schwartz wrote:

Rob == Rob Dixon [EMAIL PROTECTED] writes:

Can anybody think of an elegant solution?


Rob eval qq($val);

s/elegant/hacky, dangerous, broken/

Consider $val = ), $yourcode_here, (.


Old news, out of context, petulant.

Rob

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Interpolation of backslash-escapes

[Peter Daum]

I am looking for an way to interpolate backslash-sequences
within a string with the usual perl semantics, e.g.
$s='1\t\2\t3\na\ b c' should become:
'1tab2tab3
a b c'

Things I tried were for example
$s= eval('' . $val); # (hoping to trigger the normal interpolation) or
$s=~ s/\\(.)/\\$1/eg;
but somehow i couldn't get it right ...

Can anybody think of an elegant solution?

Regards,
 Peter Daum


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Re: Interpolation of backslash-escapes

[D. Bolliger]

Peter Daum am Freitag, 3. November 2006 20:26:

Hoi Peter,

 I am looking for an way to interpolate backslash-sequences
 within a string with the usual perl semantics, e.g.
 $s='1\t\2\t3\na\ b c' should become:
 '1tab2tab3
 a b c'

With usual perl semantics, the result is different :-)

 Things I tried were for example
  $s= eval('' . $val); # (hoping to trigger the normal interpolation) or
 $s=~ s/\\(.)/\\$1/eg;
 but somehow i couldn't get it right ...

 Can anybody think of an elegant solution?

I think there are more elegant solutions, but in the following you have full 
control over what translates to what:

#!/usr/bin/perl

use strict;
use warnings;

my %trans=(
  '\t'=\t,
  '\n'=\n,
  '\ '=' ',
  '\2'='2',
  q(\\)=qw( \ ), # ;-)
);

my $s='1\t\2\t3\na\ b c \\\ '; # last space: ;-)

$s=~s; (\\.) ; $trans{$1} || $1 ;gex;

print $s\n;

# Note the usual perl semantics:
print \2\ \n;

__END__

Dani

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Re: Interpolation of backslash-escapes

[Tom Phoenix]

On 11/3/06, Peter Daum [EMAIL PROTECTED] wrote:


I am looking for an way to interpolate backslash-sequences
within a string with the usual perl semantics


That's what eval does, although you have to build your string with
care. Don't let the user put their own data into that string; they can
(accidentally or intentionally) crash your program or worse, if you
use eval.

A better way would be to interpolate only the sequences that you need
to support. I'd write a subroutine to do that, returning the converted
string. It's simple to loop over the input string and build the new
string as you go, and it completely avoids the riskiness of eval.

Hope this helps!

--Tom Phoenix
Stonehenge Perl Training

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Re: Interpolation of backslash-escapes

[Rob Dixon]

Peter Daum wrote:


I am looking for an way to interpolate backslash-sequences
within a string with the usual perl semantics, e.g.
$s='1\t\2\t3\na\ b c' should become:
'1tab2tab3
a b c'

Things I tried were for example
$s= eval('' . $val); # (hoping to trigger the normal interpolation) or
$s=~ s/\\(.)/\\$1/eg;
but somehow i couldn't get it right ...

Can anybody think of an elegant solution?


eval qq($val);

But note that the \2 in your string (I don't know if it's a typo) will become
a character with an octal value of 2, i.e. the ASCII STX control character.

HTH,

Rob

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Re: Interpolation of backslash-escapes

[John W. Krahn]

Peter Daum wrote:
 I am looking for an way to interpolate backslash-sequences
 within a string with the usual perl semantics, e.g.
 $s='1\t\2\t3\na\ b c' should become:
 '1tab2tab3
 a b c'
 
 Things I tried were for example
 $s= eval('' . $val); # (hoping to trigger the normal interpolation) or
 $s=~ s/\\(.)/\\$1/eg;
 but somehow i couldn't get it right ...
 
 Can anybody think of an elegant solution?

$ perl -le'
my %translate = (
t = \t,
n = \n,
r = \r,
f = \f,
b = \b,
a = \a,
e = \e,
);
my $s = q[1\t\2\t3\na\ b c];
print $s;
$s =~ s/\\(.)/ exists $translate{ $1 } ? $translate{ $1 } : $1 /seg;
print $s;
'
1\t\2\t3\na\ b c
1   2   3
a b c



John
-- 
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certain sorts of tools at low cost and in short order.   -- Larry Wall

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Re: Interpolation of backslash-escapes

[Rob Dixon]

Rob Dixon wrote:

 Peter Daum wrote:

 I am looking for an way to interpolate backslash-sequences
 within a string with the usual perl semantics, e.g.
 $s='1\t\2\t3\na\ b c' should become:
 '1tab2tab3
 a b c'

 Things I tried were for example
 $s= eval('' . $val); # (hoping to trigger the normal interpolation) or
 $s=~ s/\\(.)/\\$1/eg;
 but somehow i couldn't get it right ...

 Can anybody think of an elegant solution?

 eval qq($val);

 But note that the \2 in your string (I don't know if it's a typo) will
 become
 a character with an octal value of 2, i.e. the ASCII STX control character.

I need to add that that solution relies on any parentheses in the string being 
in matching pairs. If you try


$val = ')(';

then it just won't work. If that's a problem, then you can use different
delimiters, which are guaranteed to be either escaped or not in the string at
all. The tilde is a useful one:

eval qq~$val~;

or if you're relaly stuck, then any character at all will do, including control 
characters:


eval qq\0$val\0;

works fine and delimits the string with null characters,

Cheers,

Rob


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interpolation problems (was: Re: help in regular expression)

[Dr.Ruud]

Irfan J Sayed schreef:


 #!/usr/local/bin/perl

  use warnings;
  use strict;

Good!


  my $file = c:\backup.pl;

Use

  my $file = 'c:\backup.pl';

or rather

  my $file = 'c:/backup.pl';


  open(FH,$file) || die  can't open a file;

Make that:

  open my $fh, '', $file  or  die Error opening '$file': $! ;


  my $pattern = '\w\s\w';

   my $pattern = qr/\w\s\w/ ;


  my $input = ;
  print yes got the match  if $input =~ /$pattern/;

Try this:

   while ( $fh ) {
 /$pattern/ and printf match in line %s\n, $. ;
   }


 but  i am getting following error

 Name main::FH used only once: possible typo at C:\irfan\search.pl


   close $fh  or  die Error closing '$file': $! ;

-- 
Affijn, Ruud

Gewoon is een tijger.



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Re: What is Variable Interpolation [was: Re: Help Required on the Script]

[D. Bolliger]

John W. Krahn am Freitag, 7. April 2006 01.09:
 D. Bolliger wrote:
  btw, @04 is not a valid (array) variable name; they must not start with a
  digit, as not keyword/builtin does.

 $ perl -Mwarnings -Mstrict -le' our @04 = 10 .. 14; print @04'
 10 11 12 13 14

 You are probably thinking scalars and/or lexicals.

John, 
yes I did:

$ perl -Mwarnings -Mstrict -le' my @04 = 10 .. 14; print @04'
Can't use global @04 in my at -e line 1, near my @04 
[...]

Now I get the idea of the hint in the error I was (for a too short time) 
wondering about!

Thanks!

Dani

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What is Variable Interpolation [was: Re: Help Required on the Script]

[D. Bolliger]

Mazhar am Donnerstag, 6. April 2006 11.48:
 thanks Raymond for the help it works,
 and what do u mean by variable interpolation

Hello Mazhar

It will help you a lot to know and use the documentation system of perl. 
You can get an overview by typing (on the command line):

perldoc perl
(docs)

perldoc perldoc 
(documentation system)

For your question with interpolatation, see

perldoc perlop
(and there Quote and Quote-like Operators and 
Regexp Quote-Like Operators)

For builtin funtions (here, the example is q):

perldoc -f q

Some questions are answered by

perldoc -q your question or some word(s) of the question

The online docs can be found at http://www.perl.org/docs.html

Variable interpolation is expanding variable values into a string, done by 
double quotes (or qq). Think about the following code (run in from command 
line):

perl -le '
  use strict; use warnings;
  my $word=q{Tip: };
  my @words=qw/ look at the docs /;
  print q($word @words), \n;
  print qq($word @words\n);
'

btw, @04 is not a valid (array) variable name; they must not start with a 
digit, as not keyword/builtin does.

Other tips: When asking questions,
- choose an apropriate subject line
- snip away irrelevant parts of the post


HTH!

Dani

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Re: What is Variable Interpolation [was: Re: Help Required on the Script]

[John W. Krahn]

D. Bolliger wrote:
 
 btw, @04 is not a valid (array) variable name; they must not start with a 
 digit, as not keyword/builtin does.

$ perl -Mwarnings -Mstrict -le' our @04 = 10 .. 14; print @04'
10 11 12 13 14

You are probably thinking scalars and/or lexicals.


John
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program
fulfillment

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Re: interpolation

[Shawn Corey]

John Doe wrote:

The Ghost am Montag, 16. Januar 2006 06.34:


I am storing text stings in a database.  when I have the string:

'some perl $variable'

which would print as:

some perl $variable

how can I force interpolation of '$variable'?

one idea I thought of was:
#!/usr/bin/perl
my $var='variable';
$string='some $var';
$string=~s/\$(\w+)/${$1}/gi;
print $string\n;

But it doesn't work.  I want it to print some variable.



One way is to change the regex a bit:

#!/usr/bin/perl
use strict;
use warnings;

my $var='variable';
my $other_var='another';
my ($string1, $string2, $string3)=map 'some $var $other_var', 1..3; 


# test1, test2, final version:
#
$string1=~s/(\$\w+)/$1/g;
$string2=~s/(\$\w+)/$1/ge;
$string3=~s/(\$\w+)/$1/gee;

print join \n, $string1, $string2, $string3;


greetings
joe



Usually it is considered a bad idea to interpolate external strings. You 
could have your users printing any variable. Consider using sprintf 
instead (see `perldoc -f sprintf`).


my $format = 'some perl %s';
my $string = sprintf $format, $variable;
print $string\n;


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   --- Shawn

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* Perl tutorials at http://perlmonks.org/?node=Tutorials
* A searchable perldoc is available at http://perldoc.perl.org/

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Re: interpolation

[John Doe]

Shawn Corey am Montag, 16. Januar 2006 16.55:
 John Doe wrote:
  The Ghost am Montag, 16. Januar 2006 06.34:
 I am storing text stings in a database.  when I have the string:
 
 'some perl $variable'
 
 which would print as:
 
 some perl $variable
 
 how can I force interpolation of '$variable'?
 
 one idea I thought of was:
 #!/usr/bin/perl
 my $var='variable';
 $string='some $var';
 $string=~s/\$(\w+)/${$1}/gi;
 print $string\n;
 
 But it doesn't work.  I want it to print some variable.
 
  One way is to change the regex a bit:
 
  #!/usr/bin/perl
  use strict;
  use warnings;
 
  my $var='variable';
  my $other_var='another';
  my ($string1, $string2, $string3)=map 'some $var $other_var', 1..3;
 
  # test1, test2, final version:
  #
  $string1=~s/(\$\w+)/$1/g;
  $string2=~s/(\$\w+)/$1/ge;
  $string3=~s/(\$\w+)/$1/gee;
 
  print join \n, $string1, $string2, $string3;
 
 
  greetings
  joe

 Usually it is considered a bad idea to interpolate external strings. You
 could have your users printing any variable. Consider using sprintf
 instead (see `perldoc -f sprintf`).

 my $format = 'some perl %s';
 my $string = sprintf $format, $variable;
 print $string\n;

As I understood The Ghost, the starting point string already contains a 
literal '$variable': 'some perl $variable'.

I do not know the bigger picture of his problem, but I think an extensible way 
to replace a set of known names within a string by values would be (mirco 
templating system):

===
#!/usr/bin/perl
use strict;
use warnings;

my %lookup=( 
   var='variable',
   other_var='another',
);

sub err {warn q(Unkown name '), shift, qq(' found\n)}

my $string='some $var $other_var $unknown';
$string=~s
   { \$([a-zA-Z_]+) }
   { exists $lookup{$1} ? $lookup{$1} : do {err($1), ''} }gxe;
print $string;
===

# prints: 
Unkown name 'unknown' found
some variable another

No interpolation involved, and the '$' sign preceding the names could be 
another one.

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Re: interpolation

[John Doe]

The Ghost am Freitag, 13. Januar 2006 21.23:
 I know I could do that, but what if I don't know the variable names
 in the string?

  $sql=~s/\$Status/$Status/;

 could I do:
 $sql=~s/\$(\S+)/${$1}/;

 On Jan 10, 2006, at 5:57 PM, John Doe wrote:
  The Ghost am Dienstag, 10. Januar 2006 21.57:
  I want to pull some text from a database:
 
  RxNumber in (select RxNumber FROM restoreReports WHERE Status in
  $Status)
 
  then I want perl to use this string and interpolate the variables
  ($Status).
 
  so:
 
  my $Status= ('New','Old');
  my $sql=get_SQL_String(); #will get 'RxNumber in (select RxNumber
  FROM restoreReports WHERE Status in $Status)'
 
  $sql=~s/\$Status/$Status/;
 
  (first time as literal string, second time as perl variable defined
  in the
  surrounding context)
 
  see
 
  perldoc perlre
 
  print $sql;
 
  # should print:
 
  RxNumber in (select RxNumber FROM restoreReports WHERE Status in
  ('New','Old'))
 
 
  What can I do?

Could you reformulate your (top posted) question?
What do you mean exactly by not knowing the variable names in the string?
- $Status (chars in the string) and/or 
- Status (mysql) and/or 
- $Status (in the perl code)?


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Re: interpolation

[The Ghost]

I am storing text stings in a database.  when I have the string:

'some perl $variable'

which would print as:

some perl $variable

how can I force interpolation of '$variable'?

one idea I thought of was:
#!/usr/bin/perl

my $var='variable';
$string='some $var';
$string=~s/\$(\w+)/${$1}/gi;
print $string\n;


But it doesn't work.  I want it to print some variable.


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Re: interpolation

[John Doe]

The Ghost am Montag, 16. Januar 2006 06.34:
 I am storing text stings in a database.  when I have the string:

 'some perl $variable'

 which would print as:

 some perl $variable

 how can I force interpolation of '$variable'?

 one idea I thought of was:
 #!/usr/bin/perl
 my $var='variable';
 $string='some $var';
 $string=~s/\$(\w+)/${$1}/gi;
 print $string\n;

 But it doesn't work.  I want it to print some variable.

One way is to change the regex a bit:

#!/usr/bin/perl
use strict;
use warnings;

my $var='variable';
my $other_var='another';
my ($string1, $string2, $string3)=map 'some $var $other_var', 1..3; 

# test1, test2, final version:
#
$string1=~s/(\$\w+)/$1/g;
$string2=~s/(\$\w+)/$1/ge;
$string3=~s/(\$\w+)/$1/gee;

print join \n, $string1, $string2, $string3;


greetings
joe

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Re: interpolation

[The Ghost]

I know I could do that, but what if I don't know the variable names  
in the string?



$sql=~s/\$Status/$Status/;


could I do:
$sql=~s/\$(\S+)/${$1}/;


On Jan 10, 2006, at 5:57 PM, John Doe wrote:


The Ghost am Dienstag, 10. Januar 2006 21.57:

I want to pull some text from a database:

RxNumber in (select RxNumber FROM restoreReports WHERE Status in
$Status)

then I want perl to use this string and interpolate the variables
($Status).

so:

my $Status= ('New','Old');
my $sql=get_SQL_String(); #will get 'RxNumber in (select RxNumber
FROM restoreReports WHERE Status in $Status)'


$sql=~s/\$Status/$Status/;

(first time as literal string, second time as perl variable defined  
in the

surrounding context)

see

perldoc perlre


print $sql;

# should print:

RxNumber in (select RxNumber FROM restoreReports WHERE Status in
('New','Old'))


What can I do?


hth,
joe

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string interpolation when reading from a file

[Dan Huston]

Greetings --

I am reading text sql commands) from a file, chopping it into sections 
and then writing each section out to a different file. Within the text 
are perl variables that I had expected to be interpolated as they were 
written out to the new file but they are not.


Here is a sample line:

REVOKE SELECT ON $TABLE_NAME FROM PUBLIC;

$TABLE_NAME for example might be 'STUDENTS'. 

Is there a reason that the text is not being interpolated when before it 
is written out to the new file (either when it is read in or when it is 
printed out)?


Here is a piece of my code:


##CODE SNIPPET   #

for $k ( @these_lines ) {

   # for debugging
   print $TABLE_NAME\n;
   print K\t=\t$k\n;

### SQL_OUT is the filehandle that I am writing to
   print SQL_OUT $k\n;

} ### CLOSE-FOR-K


produces this output in STDOUT:

TABLE_NAME  =  STUDENTS
K   =   REVOKE SELECT ON $TABLE_NAME FROM PUBLIC;

where I want to have :

K   =   REVOKE SELECT ON STUDENTS FROM PUBLIC;


##CODE SNIPPET   #


Thanks
Dan


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interpolation

[The Ghost]

I want to pull some text from a database:

RxNumber in (select RxNumber FROM restoreReports WHERE Status in  
$Status)


then I want perl to use this string and interpolate the variables  
($Status).


so:

my $Status= ('New','Old');
my $sql=get_SQL_String(); #will get 'RxNumber in (select RxNumber  
FROM restoreReports WHERE Status in $Status)'



something.
print $sql;

# should print:

RxNumber in (select RxNumber FROM restoreReports WHERE Status in  
('New','Old'))



What can I do?

Re: interpolation

[Mike Blezien]

Try changing your $Status variable to this:

my $Status  = '(' . '' . join(',','New','Old') . '' . ')';

that should give the results desired

hope it helps.

The Ghost wrote:

I want to pull some text from a database:

RxNumber in (select RxNumber FROM restoreReports WHERE Status in  $Status)

then I want perl to use this string and interpolate the variables  
($Status).


so:

my $Status= ('New','Old');
my $sql=get_SQL_String(); #will get 'RxNumber in (select RxNumber  FROM 
restoreReports WHERE Status in $Status)'



something.
print $sql;

# should print:

RxNumber in (select RxNumber FROM restoreReports WHERE Status in  
('New','Old'))



What can I do?



--
Mike(mickalo)Blezien
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Thunder Rain Internet Publishing
Providing Internet Solutions that work!
http://thunder-rain.com/
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=


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Re: string interpolation when reading from a file

[John Doe]

Dan Huston am Dienstag, 10. Januar 2006 21.40:
 Greetings --

 I am reading text sql commands) from a file, chopping it into sections
 and then writing each section out to a different file. Within the text
 are perl variables that I had expected to be interpolated as they were
 written out to the new file but they are not.

 Here is a sample line:

 REVOKE SELECT ON $TABLE_NAME FROM PUBLIC;

 $TABLE_NAME for example might be 'STUDENTS'.

 Is there a reason that the text is not being interpolated when before it
 is written out to the new file (either when it is read in or when it is
 printed out)?

 Here is a piece of my code:


 ##CODE SNIPPET   #

 for $k ( @these_lines ) {

 # for debugging
 print $TABLE_NAME\n;
 print K\t=\t$k\n;

 ### SQL_OUT is the filehandle that I am writing to
 print SQL_OUT $k\n;

$k _itself_ is interpolated into the double quoted string: $k contains a 
string with content looking like perl vars, $k is replaced by this string. 

But there is - luckily! - no second level interpolation included (the 
variable names _in_ the string _in_ variable $k).

You would have to make the second level interpolation explicit

   my $var='hi!';
   print eval q(He said $var and disappeared);
=He said hi! and disappeared

but this is DANGEROUS since the text could contain code instead of simple 
variable names.

There may be a useful templating module on search.cpan.org.

Or you could reinvent the wheel and parse for the variable names and replace 
them with values. Something along the lines

use strict; 
use warnings;
my %vars=(TABLE_NAME='STUDENTS');
my @these_lines=('REVOKE SELECT ON $TABLE_NAME FROM PUBLIC $UNKNOWN;');
for (@these_lines) {
s/\$([_a-zA-Z]\w*)/$vars{$1} || '$'.$1/eg;
}
print @these_lines;


 } ### CLOSE-FOR-K


 produces this output in STDOUT:

 TABLE_NAME  =  STUDENTS
 K   =   REVOKE SELECT ON $TABLE_NAME FROM PUBLIC;

 where I want to have :

 K   =   REVOKE SELECT ON STUDENTS FROM PUBLIC;


 ##CODE SNIPPET   #


 Thanks
 Dan

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Re: interpolation

[John Doe]

The Ghost am Dienstag, 10. Januar 2006 21.57:
 I want to pull some text from a database:

 RxNumber in (select RxNumber FROM restoreReports WHERE Status in
 $Status)

 then I want perl to use this string and interpolate the variables
 ($Status).

 so:

 my $Status= ('New','Old');
 my $sql=get_SQL_String(); #will get 'RxNumber in (select RxNumber
 FROM restoreReports WHERE Status in $Status)'

$sql=~s/\$Status/$Status/;

(first time as literal string, second time as perl variable defined in the 
surrounding context)

see

perldoc perlre

 print $sql;

 # should print:

 RxNumber in (select RxNumber FROM restoreReports WHERE Status in
 ('New','Old'))


 What can I do?

hth,
joe

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Interpolation Problem with Matching

[RICHARDS, JIM]

I am trying to compare files names listed in a file to the actual files
in a directory.  My code is as follows:

 

Opendir(DIR,name);

@files=readdir(DIR);

 

 Open(IN,fileList);

 

While(IN) {

If(/^pattern/) {

moveFile($_);

}

}

 

Close(IN);

 

Sub moveFile() {

My [EMAIL PROTECTED];

Foreach(@files) {

If(/$src/) {

Print $_\n;

}

}

}

 

 

I know this is not the most efficient, but I do not understand why the
statement if(/$src/) is never true?  Does not seem the $src is
interpolated correctly for the match.

Why is this happening?  How can it be fixed?

 

Thanks in advance!!!

 

Jim

RE: Interpolation Problem with Matching

[Wagner, David --- Senior Programmer Analyst --- WGO]

RICHARDS, JIM wrote:
 I am trying to compare files names listed in a file to the actual
 files in a directory.  My code is as follows:
 
 
 
 Opendir(DIR,name);
 
 @files=readdir(DIR);
 
 
 
  Open(IN,fileList);
 
 
 
 While(IN) {
 
 If(/^pattern/) {
 
 moveFile($_);
 
 }
 
 }
 
 
 
 Close(IN);
 
 
 
 Sub moveFile() {
 
 My [EMAIL PROTECTED];
 
 Foreach(@files) {
 
 If(/$src/) {
Since you are using $src as the pattern, it will take any slashes it 
finds and take something like abc\g and look for abcg since a \ in pattern 
takes whatever the next character is.  So even thouhg you see abc\g, the 
pattern is looking for abcg.  Wrap the pattern in \Q$src\E which turns off any 
of the special characters.

Wags ;)

 
 Print $_\n;
 
 }
 
 }
 
 }
 
 
 
 
 
 I know this is not the most efficient, but I do not understand why the
 statement if(/$src/) is never true?  Does not seem the $src is
 interpolated correctly for the match.
 
 Why is this happening?  How can it be fixed?
 
 
 
 Thanks in advance!!!
 
 
 
 Jim



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Re: Interpolation Problem with Matching

[John W. Krahn]

RICHARDS, JIM wrote:
I am trying to compare files names listed in a file to the actual files
in a directory.  My code is as follows:
Your code won't compile.  Please add the following two lines:
use warnings;
use strict;
to the top of your program and let perl help you find the mistakes.
The best bet to solve your problem is to use a hash for the file names, 
something like:

my $filelist = '/home/jim/filelist';
open FILES, '', $filelist or die Cannot open $filelist: $!;
my %files;
while ( FILES ) {
chomp;
$files{ $_ }++;
}
close FILES;
my $dir = '/home/jim/somedir';
opendir DIR, $dir or die Cannot open $dir: $!;
while ( my $file = readdir DIR ) {
if ( exists $files{ $file } ) {
print $file\n;
}
}
closedir DIR;

John
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Variable interpolation inside an externa js file?

[Siegfried Heintze]

In my perl script I have put my javascript code in a separate file with the
extension of js. I reference it with a javascript tag in the HTML. I have
some code in there that is not in a procedure: it just executes prior to the
body of the page loading as inline statements.

Now I discover I need some of those URLs in my external javascript file to
change depending on some perl parameters.

This is not a procedure so I cannot just change some javascript procedure
parameters. Perl does not process this file so it won't do the variable
interpolation I want either.

Below is the code that is causing the problem.

I think the only way to resolve this is to cut the code below and move it to
the perl code where I can use interpolation (which I would prefer not to do
because it will really clutter up the main program -- oh well).

Can anyone suggest a better approach?

Thanks,
  Siegfried


if (document.images) {
  one_on= new Image ();
  one_on.src= http://www.decisionchannel.com/breturn2.gif;;
  one_off   = new Image();
  one_off.src   = http://www.decisionchannel.com/return2.gif;;
  two_on= new Image ();
  two_on.src= http://www.decisionchannel.com/f_bwhatbut2.gif;;
  two_off   = new Image();
  two_off.src   = http://www.decisionchannel.com/f_whatbut2.gif;;
... // more of the same
}


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Re: Variable interpolation inside an externa js file?

[Shaun Fryer]

On Mon, Nov 22, 2004 at 01:21:35PM -0700, Siegfried Heintze wrote:
 In my perl script I have put my javascript code in a separate file with the
 extension of js. I reference it with a javascript tag in the HTML. I have
 some code in there that is not in a procedure: it just executes prior to the
 body of the page loading as inline statements.
 
 Now I discover I need some of those URLs in my external javascript file to
 change depending on some perl parameters.
 
 This is not a procedure so I cannot just change some javascript procedure
 parameters. Perl does not process this file so it won't do the variable
 interpolation I want either.
 
 Below is the code that is causing the problem.
 
 I think the only way to resolve this is to cut the code below and move it to
 the perl code where I can use interpolation (which I would prefer not to do
 because it will really clutter up the main program -- oh well).
 
 Can anyone suggest a better approach?

I'd suggest loading the js file using HTML::Template. Substitute the code you
want with a TMPL_VAR /, and write some logic so that if the query string
contains foo.js (a slight oversimplification) that it loads that template,
prints it, then exits. Does that make sense to you? Anyone else?

-- 
=
 Shaun Fryer
=
 http://sourcery.ca/
 ph: 416-544-9461
=


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Partial interpolation over pattern sustitution

[J. Alejandro Ceballos Z.]

How may I avoid partial interpolation over a pattern sustitution?
My code looks like:
# searching for all matches for later use
@matches = $htmlpage =~ m/pre(.*?)\/pre/gs;
for ($i=0; $i$#matches; $i++)
  { $htmlpage =~ s/pre$matches[$i]\/pre/predefined:$i\//; }
The problem comes when the matches contains regex characters, and they try 
to be evaluated (ex. '|+--..' must be interpeted like '\|\+--\.\.').

Is the only solution implement a pre-transform regex characters?
Any better (and fine) solution?
TIA,
--
Saludos,
 J. Alejandro Ceballos Z.   |
  --+---
 http://alejandro.ceballos.info |
  [EMAIL PROTECTED] |   Estoy convencido
 ---+   de que en un principio
tel: +52 (33) 3647-7809 |   Dios hizo un mundo distinto
cel: 044 (33) 1076-4705 |   para cada hombre,
+   y que es en ese mundo,
|   que está dentro
|   de nosotros mismos,
|   donde deberíamos
|   intentar vivir.
|
|  -- Oscar Wilde
|
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RE: Partial interpolation over pattern sustitution

[Bob Showalter]

J. Alejandro Ceballos Z. wrote:
 How may I avoid partial interpolation over a pattern sustitution?
 
 My code looks like:
 
  # searching for all matches for later use
  @matches = $htmlpage =~ m/pre(.*?)\/pre/gs;
  for ($i=0; $i$#matches; $i++)
{ $htmlpage =~ s/pre$matches[$i]\/pre/predefined:$i\//; }
 
 
 The problem comes when the matches contains regex characters, and
 they try to be evaluated (ex. '|+--..' must be interpeted like
 '\|\+--\.\.'). 

You can use the following prior to entering the for loop.

   $_ = quotemeta($_) for @matches;

You could also combine the capturing and substitution something like this:

   my @matches;
   $htmlpage =~ s/pre(.*?)\/pre/push(@matches, $1) 
predefined:$#matches/geis;

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Re: second-level string interpolation

[R. Joseph Newton]

Michael C. Davis wrote:

 Hi, Apologies if I'm bringing up a repeated topic.   I searched the list
 archive and the web and nothing specific has turned up so far.

 Is there a way to defer evaluation of the contents of a here-doc-defined
 value such that one can embed variables in the here-doc and not have them
 evaluated until they are used later?  Something like this:

It looks like you have gotten some good pointers to how you can accomplish
this.  I would suggest that you give some thought to whether it is a good idea
to try this.  What do you hope to accomplish by doing this?  If you simply don't
want to have the heredoc someplace where it interferes wh the flow of code,
there is a much better, much less obfusciated way.



 code:
 -
 use strict;
 use warnings;

 my $header = 'end_of_header';
 # File: $filename
 end_of_header

 my $filename = 'xyz';
 print $header, \n; # output: want to see # File: xyz, but get # File:
 $filename

I am not sure how the above is any more clear than it would be if you assigned a
value to $filename first.



 I tried a few variations and nothing seems to work, as shown below.  (This
 RFC http://dev.perl.org/perl6/rfc/229.html from Perl 6 implies that there
 is fact no way to do this.)  Can anyone clarify.  Thank you.

How about this:

Greetings! E:\d_drive\perlStuffperl -w
use strict;
use warnings;

sub file_report_line {
   my $filename = shift;

   return END_STRING;
 # File: $filename
END_STRING
}

my $filename = 'xyz';
print file_report_line($filename), \n

^Z
 # File: xyz

Of course, the above code is rather senseless anyway, since it could be much
more clearly written:
  return File:  $filename;
without all the baggage, but I am assuming that there is a bit more substance to
your real heredoc.

I still can't see a good reason for putting that low-level implementation detail
at the top of the script, but this approach should work.

Joseph


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Re: second-level string interpolation

[Michael C. Davis]

At 10:39 AM 3/13/04 -0800, R. Joseph Newton wrote:
 my $header = 'end_of_header';
 # File: $filename
 end_of_header

 my $filename = 'xyz';
 print $header, \n; # output: want to see # File: xyz, but get # File:
 $filename

I am not sure how the above is any more clear than it would be if you
assigned a
value to $filename first.

Mainly that $filename would have different values at different times, in
different code locations.

I still can't see a good reason for putting that low-level implementation
detail
at the top of the script, but this approach should work.

I agree, your approach is better at avoiding hidden dependencies and at
keeping code and data closer together.



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second-level string interpolation

[Michael C. Davis]

Hi, Apologies if I'm bringing up a repeated topic.   I searched the list
archive and the web and nothing specific has turned up so far.

Is there a way to defer evaluation of the contents of a here-doc-defined
value such that one can embed variables in the here-doc and not have them
evaluated until they are used later?  Something like this:

code:
-
use strict;
use warnings;

my $header = 'end_of_header';
# File: $filename
end_of_header

my $filename = 'xyz';
print $header, \n; # output: want to see # File: xyz, but get # File:
$filename


I tried a few variations and nothing seems to work, as shown below.  (This
RFC http://dev.perl.org/perl6/rfc/229.html from Perl 6 implies that there
is fact no way to do this.)  Can anyone clarify.  Thank you.

code:
-
use strict;
use warnings;

my $header = 'end_of_header';
# File: $filename
end_of_header

my $filename = test;

print $header, \n;
print eval { $header }, \n;
print $header, \n;

print eval { $header }, \n;
print ((eval $header) .\n);

output [ .. editted for readability .. ]:
---

# File: $filename
# File: $filename
# File: $filename
# File: $filename
Use of uninitialized value in concatenation (.) or string at
..\perlt\testevalsimple.pl line 15.


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Re: second-level string interpolation

[david]

Michael C. Davis wrote:

 
 Is there a way to defer evaluation of the contents of a here-doc-defined
 value such that one can embed variables in the here-doc and not have them
 evaluated until they are used later?  Something like this:
 
 code:
 -
 use strict;
 use warnings;
 
 my $header = 'end_of_header';
 # File: $filename
 end_of_header
 
 my $filename = 'xyz';
 print $header, \n; # output: want to see # File: xyz, but get #
 File:
 $filename
 
 
 I tried a few variations and nothing seems to work, as shown below.  (This
 RFC http://dev.perl.org/perl6/rfc/229.html from Perl 6 implies that there
 is fact no way to do this.)  Can anyone clarify.  Thank you.

i didn't check the link but from what you describe, i don't see any reason 
this can't be done:

#!/usr/bin/perl -w
use strict;

my $s ='CODE';
I want to say: $v
CODE

my $v = 'hello world';

print eval qq.qq,$s,.;

__END__

prints:

I want to say: hello world

david
-- 
s$s*$+/tgmecJntgRtgjvqpCvuwL$;$;=qq$
\x24\x5f\x3d\x72\x65\x76\x65\x72\x73\x65
\x24\x5f\x3b\x73\x2f\x2e\x2f\x63\x68\x72
\x28\x6f\x72\x64\x28\x24\x26\x29\x2d\x32
\x29\x2f\x67\x65\x3b\x70\x72\x69\x6e\x74
\x22\x24\x5f\x5c\x6e\x22\x3b\x3b$;eval$;

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RE: second-level string interpolation

[Wagner, David --- Senior Programmer Analyst --- WGO]

Michael C. Davis wrote:
 Hi, Apologies if I'm bringing up a repeated topic.   I searched the
 list archive and the web and nothing specific has turned up so far.
 
 Is there a way to defer evaluation of the contents of a
 here-doc-defined value such that one can embed variables in the
 here-doc and not have them evaluated until they are used later? 
 Something like this: 
 
When you need to do something like that, I give them names like: myfilename

Then do a $header =~ s/myfilename/$filename/gi;  at the point you want to do 
the print.
Now if doing more than once, then would wnat to put into secondardy variable 
to do the changes.


 code:
 -
 use strict;
 use warnings;
 
 my $header = 'end_of_header';
 # File: $filename
#File: myfilename

 end_of_header
 
 my $filename = 'xyz';
 $header =~ s/myfilename/$filename/gi;
 print $header, \n; # output: want to see # File: xyz, but get #
 File: $filename

The reason you are getting $filename in this instance has to do with using 
single ' vs double . If double had been used then  you would have had:
File: 

Wags ;)
 
 
 I tried a few variations and nothing seems to work, as shown below. 
 (This RFC http://dev.perl.org/perl6/rfc/229.html from Perl 6 implies
 that there is fact no way to do this.)  Can anyone clarify.  Thank
 you. 
 
 code:
 -
 use strict;
 use warnings;
 
 my $header = 'end_of_header';
 # File: $filename
 end_of_header
 
 my $filename = test;
 
 print $header, \n;
 print eval { $header }, \n;
 print $header, \n;
 
 print eval { $header }, \n;
 print ((eval $header) .\n);
 
 output [ .. editted for readability .. ]:
 ---
 
 # File: $filename
 # File: $filename
 # File: $filename
 # File: $filename
 Use of uninitialized value in concatenation (.) or string at
 ..\perlt\testevalsimple.pl line 15.



  Any questions and/or problems, please let me know.

  Thanks.

Wags ;)
Int: 9-8-002-2224
Ext: 408-323-4225x2224



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Re: second-level string interpolation

[Randy W. Sims]

On 03/12/04 16:35, david wrote:
Michael C. Davis wrote:


Is there a way to defer evaluation of the contents of a here-doc-defined
value such that one can embed variables in the here-doc and not have them
evaluated until they are used later?  Something like this:
   code:
   -
   use strict;
   use warnings;
   my $header = 'end_of_header';
   # File: $filename
   end_of_header
   my $filename = 'xyz';
   print $header, \n; # output: want to see # File: xyz, but get #
   File:
$filename
I tried a few variations and nothing seems to work, as shown below.  (This
RFC http://dev.perl.org/perl6/rfc/229.html from Perl 6 implies that there
is fact no way to do this.)  Can anyone clarify.  Thank you.


i didn't check the link but from what you describe, i don't see any reason 
this can't be done:

#!/usr/bin/perl -w
use strict;
my $s ='CODE';
I want to say: $v
CODE
my $v = 'hello world';

print eval qq.qq,$s,.;

__END__

prints:

I want to say: hello world

david
To elaborate a bit, the reason for the failure is that while the string 
is interpolated, it is then also evaluated as perl code, so in

my $header = 'end_of_header';
# File: $filename
end_of_header
my $filename = 'xyz';

print eval $header;

the last statement ends up looking something like:

print # File: xyz;

which of course generates an error. The solution as David points out is 
to surround $header with double quotes. There are several ways to do this:

$header = '' . $header . ''; # double quote the string in $header
print eval $header;
-or-

print eval \$header\;

-or-

print eval qq($header);

-or-

print eval qq($header);

etc.

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Re: second-level string interpolation

[John W. Krahn]

Michael C. Davis wrote:
 
 Hi, Apologies if I'm bringing up a repeated topic.   I searched the list
 archive and the web and nothing specific has turned up so far.
 
 Is there a way to defer evaluation of the contents of a here-doc-defined
 value such that one can embed variables in the here-doc and not have them
 evaluated until they are used later?  Something like this:


perldoc -q How can I expand variables in text strings



John
-- 
use Perl;
program
fulfillment

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Re: second-level string interpolation

[Randy W. Sims]

On 03/12/04 16:08, Randy W. Sims wrote:

To elaborate a bit, the reason for the failure is that while the string 
is interpolated, it is then also evaluated as perl code, so in

my $header = 'end_of_header';
# File: $filename
end_of_header
my $filename = 'xyz';

print eval $header;

the last statement ends up looking something like:

print # File: xyz;

I just realized that this might be a little misleading. If you break it 
down to:

my $result = eval $header;
print $result;
You will get an uninitialized value error. What happens is that

eval $header

is first interpolated to

eval { # File: xyz }

which is executed as perl code. As perl code this is a comment and so 
produces no value, so $result ends up with no value, which is then 
printed in the next line, generating the uninitialized value error.

Regards,
Randy.
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Re: second-level string interpolation

[david]

Randy W. Sims wrote:

 I just realized that this might be a little misleading. If you break it
 down to:
 
 my $result = eval $header;
 print $result;
 
 You will get an uninitialized value error. What happens is that
 
 eval $header
 
 is first interpolated to
 
 eval { # File: xyz }
 
 which is executed as perl code. As perl code this is a comment and so
 produces no value, so $result ends up with no value, which is then
 printed in the next line, generating the uninitialized value error.

i think you have the right idea but your example is a little misleading, 
consider:

[panda]# perl -W -le 'print eval #'

[panda]# perl -W -le 'print eval {#}'
#

similiarly, now consider:

[panda]# perl -W -le 'print eval undef'
Use of uninitialized value in eval string at -e line 1.
Use of uninitialized value in print at -e line 1.

[panda]# perl -W -le 'print eval undef'
Use of uninitialized value in print at -e line 1.

[panda]# perl -W -le 'print eval {undef}'
undef

* we got 2 warnings for the first try because undef is evaluated once and 
then returned again to print

* we got 1 warning because undef is returned from eval

* we got no warnings for the last try because the string undef is returned 
from eval

* eval{'#'} returns # not undef so your example above will not return undef

* eval EXPR vs. eval BLOCK can be found at perldoc -f eval

david
-- 
s$s*$+/tgmecJntgRtgjvqpCvuwL$;$;=qq$
\x24\x5f\x3d\x72\x65\x76\x65\x72\x73\x65
\x24\x5f\x3b\x73\x2f\x2e\x2f\x63\x68\x72
\x28\x6f\x72\x64\x28\x24\x26\x29\x2d\x32
\x29\x2f\x67\x65\x3b\x70\x72\x69\x6e\x74
\x22\x24\x5f\x5c\x6e\x22\x3b\x3b$;eval$;

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Re: second-level string interpolation

[Michael C. Davis]

Thanks everyone for the great ideas.



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OT: referencing, derefrencing, and interpolation WAS: using a CONSTANT as a pathname

[Todd W]

Tassilo Von Parseval [EMAIL PROTECTED] wrote in
message news:[EMAIL PROTECTED]
 On Sun, Jun 01, 2003 at 08:36:34PM -0400 Todd Wade wrote:

  Tassilo Von Parseval [EMAIL PROTECTED] wrote in
  message news:[EMAIL PROTECTED]
   On Sun, Jun 01, 2003 at 11:22:32AM +0200 Kevin Pfeiffer wrote:
  
  snip /
  
   open DATA, @{[ CFG ]} or die ...;
  
   The part between @{[ ]} is arbitry Perl-code that is executed in list
   context and the last expression evaluated in this Perl code is what
gets
   eventually printed.
  

After a little research, @{[ ... ]} will interpolate as the perl
equivalent of:

join($, @{[ ... ]})

and then return in the string. To get the behavior you describe above, one
would use the code you provided below from the last post =0)

note:

[EMAIL PROTECTED] wadet]$ perl
$ = '-';
print( time is: ${ \localtime }\n );
print( time is: @{ [localtime] }\n );
Ctrl-D
time is: 1
time is: 13-24-6-2-5-103-1-152-1


  If you want to interpolate a scalar value in a string you should
probably
  avoid creating an array reference, if only to avoid confusion:
 
  [EMAIL PROTECTED] trwww]$ perl
  use constant A_CONSTANT = '/some/path';
  print(the constant's value is: ${ \A_CONSTANT }\n);
  Ctrl-D
  the constant's value is: /some/path

 That's a bit better here because ${ \... } will execute the code in
 scalar-context instead of list-context. However, it wont always work as
 expected which is why I seldom use it. For instance:

 # this should work _theoretically_
 print ${ \localtime };
 # but doesn't:
 __END__
 1


This is the code that evaluates the expression and returns its last element
to the \ operator, But only because the argument is a list, and not an
array.

Ive done a s/expected/defined/g on the way I code and things started working
better for me =0)

Im clarifying my thoughts and not yours... Im still a bit unsure, but I have
to get to work now.

Todd W.




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RE: Best way to stop array interpolation.

[Bob Showalter]

Bakken, Luke wrote:
 Here's a quickie:
 
 I need to create a hash index out of a string that looks like this:
 
 loans:a_foo[0]
 
 If I build the index like this:
 
 $rec-{loans:a_$fld[$i]} = $tmp{$fld} || '';
 
 perl thinks that $fld[$i] is an array element, which it isn't.
 
 Here are two solutions I found:
 
 $rec-{loans:a_$fld . [$i]} = $tmp{$fld} || '';
 $rec-{loans:a_$fld\[$i]} = $tmp{$fld} || '';
 
 Are there any other ways? Just curious.

loans:a_${fld}[$i] also works. I like your second version above best.

$ perl -MO=Deparse,-q -e 'a_${fld}[$i]'
'a_' . $fld . '[' . $i . ']';

$ perl -MO=Deparse,-q -e 'a_$fld\[$i]'
'a_' . $fld . '[' . $i . ']';

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Best way to stop array interpolation.

[Bakken, Luke]

Here's a quickie:

I need to create a hash index out of a string that looks like this:

loans:a_foo[0]

If I build the index like this:

$rec-{loans:a_$fld[$i]} = $tmp{$fld} || '';

perl thinks that $fld[$i] is an array element, which it isn't.

Here are two solutions I found:

$rec-{loans:a_$fld . [$i]} = $tmp{$fld} || '';
$rec-{loans:a_$fld\[$i]} = $tmp{$fld} || '';

Are there any other ways? Just curious.
Luke

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RE: Best way to stop array interpolation.

[Bakken, Luke]

  Here are two solutions I found:
  
  $rec-{loans:a_$fld . [$i]} = $tmp{$fld} || '';
  $rec-{loans:a_$fld\[$i]} = $tmp{$fld} || '';
  
  Are there any other ways? Just curious.
 
 loans:a_${fld}[$i] also works. I like your second version 
 above best.
 
 $ perl -MO=Deparse,-q -e 'a_${fld}[$i]'
 'a_' . $fld . '[' . $i . ']';
 
 $ perl -MO=Deparse,-q -e 'a_$fld\[$i]'
 'a_' . $fld . '[' . $i . ']';

Hmm you know that was the first thing I tried, but I always get this
error, indicating it's still looking for @fld:

I also have use strict on.

C:\tmpperl testadr
Global symbol @fld requires explicit package name at testadr line 37.
Global symbol @fld requires explicit package name at testadr line 43.
BEGIN not safe after errors--compilation aborted at testadr line 48. 

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RE: Best way to stop array interpolation.

[Bob Showalter]

Bakken, Luke wrote:
   Here are two solutions I found:
   
   $rec-{loans:a_$fld . [$i]} = $tmp{$fld} || '';
   $rec-{loans:a_$fld\[$i]} = $tmp{$fld} || '';
   
   Are there any other ways? Just curious.
  
  loans:a_${fld}[$i] also works. I like your second version above
  best. 
  
  $ perl -MO=Deparse,-q -e 'a_${fld}[$i]'
  'a_' . $fld . '[' . $i . ']';
  
  $ perl -MO=Deparse,-q -e 'a_$fld\[$i]'
  'a_' . $fld . '[' . $i . ']';
 
 Hmm you know that was the first thing I tried, but I always get this
 error, indicating it's still looking for @fld:
 
 I also have use strict on.
 
 C:\tmpperl testadr
 Global symbol @fld requires explicit package name at testadr line
 37. Global symbol @fld requires explicit package name at testadr
 line 43. BEGIN not safe after errors--compilation aborted at testadr
 line 48. 

You're right. I guess what I wrote is a no-no.

Writing something like ${fld}foo is like $fld . foo

But the opening square bracket seems to cause problems with strict turned
on. Maybe somebody smarter than me (shouldn't be hard to find!) can explain
further.


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Re: Help with Hash values and variable interpolation

[badchoice]

 112.58.26.32.32770  192.35.51.30.53:  64596[|domain] (DF)
 112.58.26.32.32770  192.100.59.110.53:  24685 [1au][|domain] (DF)
 112.58.26.4.2506  216.148.227.69.80: . ack 3280436924 win 2920 (DF)
 112.58.26.4.2506  216.148.227.69.80: . ack 1759 win 1162 (DF)
 112.58.26.4.2498  66.207.130.76.80: . ack 2195940947 win 7906 (DF)
 112.58.26.4.2498  66.207.130.76.80: R 2576805184:2576805184(0) win 0 (DF)
  

perl -ne '@a[/(\d+):/]++}{print Port 53: $a[53]\t Port 80: $a[80]\n' infile.txt
Port 53: 2   Port 80: 4

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Help with Hash values and variable interpolation

[Scott, Joshua]

Hello all,
 
I've got a file which contains ports and hostnames.  I'd like to count the
number of instances that each item occurs in my file.  I'm having a
difficult time with this.
 
This is my script:  Basically I'm splitting the first line a few times to
get the data I need.  What am I doing wrong?  At the bottom you'll find a
snippet of the file I'm parsing.  
 
Thank you for all your help!
 
###
#/usr/bin/perl -w
 
open (FILE,'c:\temp\outbound.traffic');
 
%allports=();
 
file=FILE;
 
foreach (file) {
chomp();
($source,$other,$dest) = split(/\s/,$_);
($a,$b,$c,$d,$src_port)= split(/\./,$source);
($e,$f,$g,$h,$dst_port) = split(/\./,$dest);
$sourceip = $a.$b.$c.$d;
$destip = $e.$f.$g.$h;
$dst_port =~ s/:/ /;
 
push(dstports,$dst_port);
};
 
foreach $element (dstports) {
chomp($element);
print $element\n;
$allports{$element}++;
}
 
print Port 53: $allports{53}\t Port 80: $allports{80}\n;
close (FILE);
###3
 
FILE THAT IS BEING PARSED
 
 
112.58.26.32.32770  192.35.51.30.53:  64596[|domain] (DF)
112.58.26.32.32770  192.100.59.110.53:  24685 [1au][|domain] (DF)
112.58.26.4.2506  216.148.227.69.80: . ack 3280436924 win 2920 (DF)
112.58.26.4.2506  216.148.227.69.80: . ack 1759 win 1162 (DF)
112.58.26.4.2498  66.207.130.76.80: . ack 2195940947 win 7906 (DF)
112.58.26.4.2498  66.207.130.76.80: R 2576805184:2576805184(0) win 0 (DF)
 

==
NOTICE - This communication may contain confidential and privileged information that 
is for the sole use of the intended recipient. Any viewing, copying or distribution 
of, or reliance on this message by unintended recipients is strictly prohibited. If 
you have received this message in error, please notify us immediately by replying to 
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==

RE: Help with Hash values and variable interpolation

[Scott, Joshua]

I figured it out already!  I ran a replace on the dst_port and replaced it
with a whitespace which threw off the count.  I've modified it to delete the
whitespace and all works perfect.  


Joshua Scott
Security Systems Analyst, CISSP
626-568-7024


-Original Message-
From: Scott, Joshua [mailto:Joshua.Scott;Jacobs.com] 
Sent: Monday, November 04, 2002 5:42 PM
To: '[EMAIL PROTECTED]'
Subject: Help with Hash values and variable interpolation


Hello all,
 
I've got a file which contains ports and hostnames.  I'd like to count the
number of instances that each item occurs in my file.  I'm having a
difficult time with this.
 
This is my script:  Basically I'm splitting the first line a few times to
get the data I need.  What am I doing wrong?  At the bottom you'll find a
snippet of the file I'm parsing.  
 
Thank you for all your help!
 
###
#/usr/bin/perl -w
 
open (FILE,'c:\temp\outbound.traffic');
 
%allports=();
 
@file=FILE;
 
foreach (@file) {
chomp();
($source,$other,$dest) = split(/\s/,$_);
($a,$b,$c,$d,$src_port)= split(/\./,$source);
($e,$f,$g,$h,$dst_port) = split(/\./,$dest);
$sourceip = $a.$b.$c.$d;
$destip = $e.$f.$g.$h;
$dst_port =~ s/:/ /;
 
push(@dstports,$dst_port);
};
 
foreach $element (@dstports) {
chomp($element);
print $element\n;
$allports{$element}++;
}
 
print Port 53: $allports{53}\t Port 80: $allports{80}\n; close (FILE);
###3
 
FILE THAT IS BEING PARSED
 
 
112.58.26.32.32770  192.35.51.30.53:  64596[|domain] (DF)
112.58.26.32.32770  192.100.59.110.53:  24685 [1au][|domain] (DF)
112.58.26.4.2506  216.148.227.69.80: . ack 3280436924 win 2920 (DF)
112.58.26.4.2506  216.148.227.69.80: . ack 1759 win 1162 (DF)
112.58.26.4.2498  66.207.130.76.80: . ack 2195940947 win 7906 (DF)
112.58.26.4.2498  66.207.130.76.80: R 2576805184:2576805184(0) win 0 (DF)
 


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error, please notify us immediately by replying to the message and deleting
it from your computer.


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error, please notify us immediately by replying to the message and deleting
it from your computer.


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you have received this message in error, please notify us immediately by replying to 
the message and deleting it from your computer.

==


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Re: Help with Hash values and variable interpolation

[John W. Krahn]

Joshua Scott wrote:
 
 Hello all,

Hello,

 I've got a file which contains ports and hostnames.  I'd like to count the
 number of instances that each item occurs in my file.  I'm having a
 difficult time with this.
 
 This is my script:  Basically I'm splitting the first line a few times to
 get the data I need.  What am I doing wrong?  At the bottom you'll find a
 snippet of the file I'm parsing.
 
 Thank you for all your help!
 
 ###
 #/usr/bin/perl -w
 
 open (FILE,'c:\temp\outbound.traffic');

You should _always_ verify that the file opened successfully.  Also, you
can use slashes instead of backslashes in file names.

open FILE, 'c:/temp/outbound.traffic' or die Cannot open
'c:/temp/outbound.traffic': $!;


 %allports=();
 
 @file=FILE;
 
 foreach (@file) {

You shouldn't read the whole file into an array unless you _really_ need
to.

while ( FILE ) {

 chomp();

You don't really need to chomp as you are not using the data at the end
of the line.


 ($source,$other,$dest) = split(/\s/,$_);
 ($a,$b,$c,$d,$src_port)= split(/\./,$source);
 ($e,$f,$g,$h,$dst_port) = split(/\./,$dest);
 $sourceip = $a.$b.$c.$d;
 $destip = $e.$f.$g.$h;

  next unless my ( $source, $src_port, $dest, $dst_port ) =
  /^([\d.]+)\.(\d+)[ ]+([\d.]+)\.(\d+)/;


 $dst_port =~ s/:/ /;
 
 push(@dstports,$dst_port);

  print $dst_port\n;
  $allports{$dst_port}++;

 };
 
 foreach $element (@dstports) {
 chomp($element);
 print $element\n;
 $allports{$element}++;
 }
 
 print Port 53: $allports{53}\t Port 80: $allports{80}\n;
 close (FILE);
 ###3
 
 FILE THAT IS BEING PARSED
 
 112.58.26.32.32770  192.35.51.30.53:  64596[|domain] (DF)
 112.58.26.32.32770  192.100.59.110.53:  24685 [1au][|domain] (DF)
 112.58.26.4.2506  216.148.227.69.80: . ack 3280436924 win 2920 (DF)
 112.58.26.4.2506  216.148.227.69.80: . ack 1759 win 1162 (DF)
 112.58.26.4.2498  66.207.130.76.80: . ack 2195940947 win 7906 (DF)
 112.58.26.4.2498  66.207.130.76.80: R 2576805184:2576805184(0) win 0 (DF)



John
-- 
use Perl;
program
fulfillment

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Interpolation problem

[Beau E. Cox]

Hi all -

I can't figure this one out. I have a requirement
to grab from some sort of input the elements of a regular
expression and execute it. All is fine except when I use
$1, $2, ... in the substitution, as:

#!/usr/bin/perl
use strict;
use warnings;

$_ = 'beau cox';
my $match = '(\w+)\s+(\w+)';
my $sub = '$2 $1';
s /$match/$sub/;
print regex: s/$match/$sub/\nresult: $_\n\$1: $1\n\$2: $2\n;

gives the output:

regex: s/(\w+)\s+(\w+)/$2 $1/
result: $2 $1
$1: beau
$2: cox

I know the problem has something to do with my $2 $1 being
inside $sub, but...?

Aloha = Beau.

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RE: Interpolation problem

[David . Wagner]

You are using single quotes which tell Perl to NOT interpret what is
between the single quotes.  SO '$2 $1' becomes $2 $1 in the new variable
while $2 $1 would become the values of $2 and $1.

Wags ;)

-Original Message-
From: Beau E. Cox [mailto:[EMAIL PROTECTED]]
Sent: Wednesday, August 28, 2002 11:07
To: [EMAIL PROTECTED]
Subject: Interpolation problem


Hi all -

I can't figure this one out. I have a requirement
to grab from some sort of input the elements of a regular
expression and execute it. All is fine except when I use
$1, $2, ... in the substitution, as:

#!/usr/bin/perl
use strict;
use warnings;

$_ = 'beau cox';
my $match = '(\w+)\s+(\w+)';
my $sub = '$2 $1';
s /$match/$sub/;
print regex: s/$match/$sub/\nresult: $_\n\$1: $1\n\$2: $2\n;

gives the output:

regex: s/(\w+)\s+(\w+)/$2 $1/
result: $2 $1
$1: beau
$2: cox

I know the problem has something to do with my $2 $1 being
inside $sub, but...?

Aloha = Beau.

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Re: Interpolation problem

[Jeff 'japhy' Pinyan]

On Aug 28, Beau E. Cox said:

I can't figure this one out. I have a requirement
to grab from some sort of input the elements of a regular
expression and execute it. All is fine except when I use
$1, $2, ... in the substitution, as:

This is in the FAQ, and one of the MOST commonly asked FAQs I've ever
seen.

perldoc -q expand
How can I expand variables in text strings?
[...]

Long story short:

  $m = '(\w+)\s+(\w+)';  # should consider using qr/(\w+)\s+(\w+)/ instead
  $r = '$1 $2';
  s/$m/$r/ee;

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** Look for Regular Expressions in Perl published by Manning, in 2002 **
stu what does y/// stand for?  tenderpuss why, yansliterate of course.
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RE: Interpolation problem

[Beau E. Cox]

Thanks Japhy and Wags - I figured it was simple. Aloha = Beau.

-Original Message-
From: Jeff 'japhy' Pinyan [mailto:[EMAIL PROTECTED]]
Sent: Wednesday, August 28, 2002 8:18 AM
To: Beau E. Cox
Cc: [EMAIL PROTECTED]
Subject: Re: Interpolation problem


On Aug 28, Beau E. Cox said:

I can't figure this one out. I have a requirement
to grab from some sort of input the elements of a regular
expression and execute it. All is fine except when I use
$1, $2, ... in the substitution, as:

This is in the FAQ, and one of the MOST commonly asked FAQs I've ever
seen.

perldoc -q expand
How can I expand variables in text strings?
[...]

Long story short:

  $m = '(\w+)\s+(\w+)';  # should consider using qr/(\w+)\s+(\w+)/ instead
  $r = '$1 $2';
  s/$m/$r/ee;

-- 
Jeff japhy Pinyan  [EMAIL PROTECTED]  http://www.pobox.com/~japhy/
RPI Acacia brother #734   http://www.perlmonks.org/   http://www.cpan.org/
** Look for Regular Expressions in Perl published by Manning, in 2002 **
stu what does y/// stand for?  tenderpuss why, yansliterate of course.
[  I'm looking for programming work.  If you like my work, let me know.  ]


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Pattern-Matching var - interpolation.

[Angerstein]

Hello,
I have a very unfunny problem, on which i am working for hours.

I need to find out if a string contains an other specified string.
I want to use pattern-matching.
I can´t get a match together which make this. Look at my examples,
none of the Matchings using vars works. If I replaces the vars to normal
strings it works like it should.
I am using perl 5.6 on a aix 4.3.3.

Thanks for help!
 cut
#
#!/usr/bin/perl -w

my $hund= hund m-a-u-s katze k.a.t.z.e. maus xyz 1234;
my $dings1 = hund;
my $dings2 = m-a-u-s;
my $dings3 = k.a.t.z.e.;
my $dings4 = xyz;
my $dings5 = 123;

if ( $dings1 =~ /\Q$hund/) {
print $dings1 in \$hund;}

if ( $dings1 =~ /\Q${hund}/) {
print $dings1 in \$hund;}

if ( $dings3 =~ /${hund}/) {
print $dings3 in \$hund;}

if ( $dings3 =~ /\Q${hund}/) {
print $dings3 in \$hund;}

if ( $dings5 =~ /$hund/) {
print $dings5 in \$hund;}

if ( $dings1 =~ /\Q$hund/) {
print $dings1 in \$hund;}

if ( $dings1 =~ /.*\Q${hund}\E.*/) {
print $dings1 in \$hund;}

if ( $dings3 =~ /\${hund}/) {
print $dings3 in \$hund;}

if ( $dings3 =~ /.*\Q${hund}/) {
print $dings3 in \$hund;}

if ( $dings5 =~ /.*$hund.*/) {
print $dings5 in \$hund;}

if ( $dings4 =~ /.*$hund.*/) {
print $dings5 in \$hund;}
## EOF
#


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Re: Pattern-Matching var - interpolation.

[Sudarshan Raghavan]

On Fri, 19 Jul 2002, Angerstein wrote:

 Hello,
 I have a very unfunny problem, on which i am working for hours.
 
 I need to find out if a string contains an other specified string.
 I want to use pattern-matching.
 I can´t get a match together which make this. Look at my examples,
 none of the Matchings using vars works. If I replaces the vars to normal
 strings it works like it should.
 I am using perl 5.6 on a aix 4.3.3.
 
 Thanks for help!
  cut
 #
 #!/usr/bin/perl -w
 
 my $hund= hund m-a-u-s katze k.a.t.z.e. maus xyz 1234;
 my $dings1 = hund;
 my $dings2 = m-a-u-s;
 my $dings3 = k.a.t.z.e.;
 my $dings4 = xyz;
 my $dings5 = 123;
 
 if ( $dings1 =~ /\Q$hund/) {
   print $dings1 in \$hund;}

You are searching for $dings1 in $hund, this must be the other way around
if ($hund =~ /\Q$hund/)

You might also want to take a look at index (perldoc -f index). 
Note, if you are searching for 'orld' in 'Hello World' the regex will 
succeed. If you do not want this take look at '\b' in perldoc perlre

 
 if ( $dings1 =~ /\Q${hund}/) {
   print $dings1 in \$hund;}
 
 if ( $dings3 =~ /${hund}/) {
   print $dings3 in \$hund;}
 
 if ( $dings3 =~ /\Q${hund}/) {
   print $dings3 in \$hund;}
 
 if ( $dings5 =~ /$hund/) {
   print $dings5 in \$hund;}
 
 if ( $dings1 =~ /\Q$hund/) {
   print $dings1 in \$hund;}
 
 if ( $dings1 =~ /.*\Q${hund}\E.*/) {
   print $dings1 in \$hund;}
 
 if ( $dings3 =~ /\${hund}/) {
   print $dings3 in \$hund;}
 
 if ( $dings3 =~ /.*\Q${hund}/) {
   print $dings3 in \$hund;}
 
 if ( $dings5 =~ /.*$hund.*/) {
   print $dings5 in \$hund;}
 
 if ( $dings4 =~ /.*$hund.*/) {
   print $dings5 in \$hund;}
 ## EOF
 #
 
 
 


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Re: Pattern-Matching var - interpolation.

[Sudarshan Raghavan]

On Fri, 19 Jul 2002, Sudarshan Raghavan wrote:

 On Fri, 19 Jul 2002, Angerstein wrote:
 
  Hello,
  I have a very unfunny problem, on which i am working for hours.
  
  I need to find out if a string contains an other specified string.
  I want to use pattern-matching.
  I can´t get a match together which make this. Look at my examples,
  none of the Matchings using vars works. If I replaces the vars to normal
  strings it works like it should.
  I am using perl 5.6 on a aix 4.3.3.
  
  Thanks for help!
   cut
  #
  #!/usr/bin/perl -w
  
  my $hund= hund m-a-u-s katze k.a.t.z.e. maus xyz 1234;
  my $dings1 = hund;
  my $dings2 = m-a-u-s;
  my $dings3 = k.a.t.z.e.;
  my $dings4 = xyz;
  my $dings5 = 123;
  
  if ( $dings1 =~ /\Q$hund/) {
  print $dings1 in \$hund;}
 
 You are searching for $dings1 in $hund, this must be the other way around
 if ($hund =~ /\Q$hund/)

sorry, this should be if ($hund =~ /\Q$dings1/)


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variable interpolation

[bernabe diaz]

Hi everyone,
could somebody help me with the following problem:
i have a code something like that
my  $variable = CGI-param('NAME');
#making connection to database
.
my $variable_ =$dbh-quote($variable);
.

$sth = -$dbh-prepare( SELECT  something FROM some_table WHERE 
some_key=$variable_)


then when I try to pass $variable_to a SQL statment the value of 
$variable_ was not passed
so i can't fetch information fro the database.
when i give the string to the SELECT statement  directly every thing is 
fine, is working, that's why
I consider that it is a problem of interpolation of the variable .
could anybody help me
Thanks,
BD


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Re: variable interpolation

[bob ackerman]

On Friday, April 19, 2002, at 07:18  AM, bernabe diaz wrote:

 Hi everyone,
 could somebody help me with the following problem:
 i have a code something like that
 my  $variable = CGI-param('NAME');
 #making connection to database
 .
 my $variable_ =$dbh-quote($variable);
 .

 $sth = -$dbh-prepare( SELECT  something FROM some_table WHERE some_key=
 $variable_)
 

i think you need to put single quotes around $variable_.
$sth = -$dbh-prepare( SELECT  something FROM some_table WHERE some_key=
'$variable_' );


 then when I try to pass $variable_to a SQL statment the value of 
 $variable_ was not passed
 so i can't fetch information fro the database.
 when i give the string to the SELECT statement  directly every thing is 
 fine, is working, that's why
 I consider that it is a problem of interpolation of the variable .
 could anybody help me
 Thanks,
 BD


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variable interpolation

[bernabe diaz]

Thanks for help, but
I tried that way too, and it does not work.
BD

bob ackerman wrote:


 On Friday, April 19, 2002, at 07:18  AM, bernabe diaz wrote:

 Hi everyone,
 could somebody help me with the following problem:
 i have a code something like that
 my  $variable = CGI-param('NAME');
 #making connection to database
 .
 my $variable_ =$dbh-quote($variable);
 .

 $sth = -$dbh-prepare( SELECT  something FROM some_table WHERE 
 some_key=
 $variable_)
 


 i think you need to put single quotes around $variable_.
 $sth = -$dbh-prepare( SELECT  something FROM some_table WHERE 
 some_key=
 '$variable_' );


 then when I try to pass $variable_to a SQL statment the value of 
 $variable_ was not passed
 so i can't fetch information fro the database.
 when i give the string to the SELECT statement  directly every thing 
 is fine, is working, that's why
 I consider that it is a problem of interpolation of the variable .
 could anybody help me
 Thanks,
 BD


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RE: variable interpolation

[Hanson, Robert]

I prefer using a placeholder, you don't need to quote anything that way
which avoids mistakes.

my $sth = $dbh-prepare('SELECT something FROM some_table WHERE some_key =
?');
$sth-execute( CGI-param('NAME') );

Did you also print out the variable to prove that it does indeed contain
some data?  Do you also have the RaiseError attribute turned on to die if
there are any SQL errors?

Rob


-Original Message-
From: bernabe diaz [mailto:[EMAIL PROTECTED]]
Subject: variable interpolation

Thanks for help, but
I tried that way too, and it does not work.
BD

bob ackerman wrote:


 On Friday, April 19, 2002, at 07:18  AM, bernabe diaz wrote:

 Hi everyone,
 could somebody help me with the following problem:
 i have a code something like that
 my  $variable = CGI-param('NAME');
 #making connection to database
 .
 my $variable_ =$dbh-quote($variable);
 .

 $sth = -$dbh-prepare( SELECT  something FROM some_table WHERE 
 some_key=
 $variable_)
 


 i think you need to put single quotes around $variable_.
 $sth = -$dbh-prepare( SELECT  something FROM some_table WHERE 
 some_key=
 '$variable_' );
snip


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RE: variable interpolation

[Bob Showalter]

 -Original Message-
 From: bernabe diaz [mailto:[EMAIL PROTECTED]]
 Sent: Friday, April 19, 2002 10:18 AM
 To: [EMAIL PROTECTED]
 Subject: variable interpolation
 
 
 Hi everyone,
 could somebody help me with the following problem:
 i have a code something like that
 my  $variable = CGI-param('NAME');
 #making connection to database
 .
 my $variable_ =$dbh-quote($variable);
 .
 
 $sth = -$dbh-prepare( SELECT  something FROM some_table WHERE 
 ^^
 This is a syntax error, no?

 some_key=$variable_)
 
 
 then when I try to pass $variable_to a SQL statment the value of 
 $variable_ was not passed
 so i can't fetch information fro the database.
 when i give the string to the SELECT statement  directly 
 every thing is 
 fine, is working, that's why
 I consider that it is a problem of interpolation of the variable .

We can't see what the contents of $variable_ are, so we can't
tell what the problem is. What *exactly* is being passed to the 
prepare() call?

IOW, try something like this:

   my $sql = select * from foo where name=$variable_;
   print $sql, \n;
   my $sth = $dbh-prepare($sql) or die $DBI::errstr;

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Re: variable interpolation

[bernabe diaz]

Thank you very much !Now it's working!
bd.

Hanson, Robert wrote:

I prefer using a placeholder, you don't need to quote anything that way
which avoids mistakes.

my $sth = $dbh-prepare('SELECT something FROM some_table WHERE some_key =
?');
$sth-execute( CGI-param('NAME') );

Did you also print out the variable to prove that it does indeed contain
some data?  Do you also have the RaiseError attribute turned on to die if
there are any SQL errors?

Rob


-Original Message-
From: bernabe diaz [mailto:[EMAIL PROTECTED]]
Subject: variable interpolation

Thanks for help, but
I tried that way too, and it does not work.
BD

bob ackerman wrote:

On Friday, April 19, 2002, at 07:18  AM, bernabe diaz wrote:

Hi everyone,
could somebody help me with the following problem:
i have a code something like that
my  $variable = CGI-param('NAME');
#making connection to database
.
my $variable_ =$dbh-quote($variable);
.

$sth = -$dbh-prepare( SELECT  something FROM some_table WHERE 
some_key=
$variable_)



i think you need to put single quotes around $variable_.
$sth = -$dbh-prepare( SELECT  something FROM some_table WHERE 
some_key=
'$variable_' );

snip





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Variable Interpolation

[DBuitendag]

Hi .

Can you please help.

When does Interpolation occur at Compile Time , Run Time or Both.
So far I know on both, then why does the following not work. ( how can I get it
to work ?)

$scripts = 'cd $acu_home/bin \n nohup ${srv}_ss $srv.ini 
$acu_home/bin/$srv.out';
$acu_home = /luke/u01/app/rdf/product/4.1/acumate;
$srv = edg;
print(SCRIPT: $scripts \n);
system($scripts);

Thanks.

Derek





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Re: Question: Interpolation in Strings

[Jenda Krynicky]

From:   G. E. [EMAIL PROTECTED]

 As I' ve read in Programming Perl, double-quoted strings are subject
 to variable interpolation of scalars and list values. Nothing else
 interpolates. So the following perl code won't compile:
 
  $st = !--- get_header(Users)---!;
 
  sub get_header{
   $hnd-fixHead(@_);
  }

use Interpolation get_header = sub {
$hnd-fixHead(@_)
};

$st = !--- $get_header{'Users'}---!;

http://Jenda.Krynicky.cz/#Interpolation

Jenda

=== [EMAIL PROTECTED] == http://Jenda.Krynicky.cz ==
There is a reason for living. There must be. I've seen it somewhere.
It's just that in the mess on my table ... and in my brain.
I can't find it.
--- me

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Question: Interpolation in Strings

[G. E.]

As I' ve read in Programming Perl, double-quoted strings are subject to 
variable interpolation of scalars and list values. Nothing else 
interpolates.
So the following perl code won't compile:

$st = !--- get_header(Users)---!;

sub get_header{
$hnd-fixHead(@_);
}

also the following line of code won't compile (which does the same as the 
above):
$st = !--- $hnd-fixHead(Users)---!;

If I use the '.' operator (concatenation) my work is done. For example:
$st = !---  . $hnd-fixHead(Users) . ---!;

My question is if there is any way, that will let me do such an 
interpolation, without concatenation. For example I've started reading 
about overloading the stringify, but I realized that it isn't what I'm 
looking for.
Is there a way to have the return value of $hnd-fixHead(Users) 
interpolated into my string, without concatenation?

Thank you,
Giannis

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Re: Question: Interpolation in Strings

[John W. Krahn]

G. E. wrote:
 
 As I' ve read in Programming Perl, double-quoted strings are subject to
 variable interpolation of scalars and list values. Nothing else
 interpolates.
 So the following perl code won't compile:
 
 $st = !--- get_header(Users)---!;
 
 sub get_header{
 $hnd-fixHead(@_);
 }
 
 also the following line of code won't compile (which does the same as the
 above):
 $st = !--- $hnd-fixHead(Users)---!;
 
 If I use the '.' operator (concatenation) my work is done. For example:
 $st = !---  . $hnd-fixHead(Users) . ---!;
 
 My question is if there is any way, that will let me do such an
 interpolation, without concatenation. For example I've started reading
 about overloading the stringify, but I realized that it isn't what I'm
 looking for.
 Is there a way to have the return value of $hnd-fixHead(Users)
 interpolated into my string, without concatenation?


perldoc -q 'How do I expand function calls in a string'


John
-- 
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program
fulfillment

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Re: Question: Interpolation in Strings

[Jeff 'japhy' Pinyan]

On Feb 2, G. E. said:

As I' ve read in Programming Perl, double-quoted strings are subject to 
variable interpolation of scalars and list values. Nothing else 
interpolates.
So the following perl code won't compile:

   $st = !--- get_header(Users)---!;

You have quotes inside of quotes.  Try using different quotes, or using
the q// or qq// operators:

  $st = !--- @{[ get_header('Users') ]} ---!;
  $st = qq(!--- @{[ get_header(Users) ]} ---!;

For an explanation of how @{[ ... ]} works...

  1. arrays DO get interpolated in strings
  2. [ ... ] creates an array reference
  3. @{ $array_ref } dereferences an array reference
  4. @{[ ... ]} dereferences an array reference built on-the-fly
  5. @{[ ... ]} expands that array as if it were @foo

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** Look for Regular Expressions in Perl published by Manning, in 2002 **
stu what does y/// stand for?  tenderpuss why, yansliterate of course.


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Re: Variable interpolation?

[Mad B . Jones]

06/01/02 17:20:37, Jeff 'japhy' Pinyan [EMAIL PROTECTED] a écrit:

The contents of @string are raw text.  You'll need to expand the variables
in it manually:

  perldoc -q 'expand variables'

That FAQ will tell you what to do.

Thanks, Jeff, for taking the time to answer.

My problem was, as a beginner, that I didn't know where to start looking in the 
documentation, since I didn't know what the problem was :)


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Variable interpolation?

[Mad B . Jones]

Hi everyone. A little thing I fail to understand...

This of course works:
$name=Dave;
$string=Hello $name;
print $string;
outputting:
Hello Dave

Why, then, does it not work when I get the string Hello $name out of a file?
$name=Dave;
$in=textfile.txt;
open(INFILE, $in);
@string=INFILE;
$string=$string[0];
print $string;
The output is:
Hello $name

Thanks a million if anyone has the answer

Dave Jones


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Re: Variable interpolation?

[Jeff 'japhy' Pinyan]

On Jan 6, Mad B.Jones said:

$name=Dave;
$in=textfile.txt;
open(INFILE, $in);
@string=INFILE;
$string=$string[0];

The contents of @string are raw text.  You'll need to expand the variables
in it manually:

  perldoc -q 'expand variables'

That FAQ will tell you what to do.

-- 
Jeff japhy Pinyan  [EMAIL PROTECTED]  http://www.pobox.com/~japhy/
RPI Acacia brother #734   http://www.perlmonks.org/   http://www.cpan.org/
** Look for Regular Expressions in Perl published by Manning, in 2002 **
stu what does y/// stand for?  tenderpuss why, yansliterate of course.


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