Incrementing Strings
If I define a variable as a string my $var = a; I can get the increment to work print ++$var; -- prints b but the decrement print --$var -- prints -1 Why? and how can I decrement it? Thanks, -Nick _ Get your FREE download of MSN Explorer at http://explorer.msn.com
comparing strings
Does anyone know a way to make boolean comparisons between strings? For example, I want 'a' 'b' to be true, but perl says 'a' == 'b' is true. Thanks, -Nick _ Get your FREE download of MSN Explorer at http://explorer.msn.com
=
I have written some OO perl and I have a problem that I just realized, when you set an object = to another object, they become irreversibly linked and all operations on one or the other causes changes in both. If I am trying to simply initialize the object and not link them, how do I get around this problem? Thanks, -Nick _ Get your FREE download of MSN Explorer at http://explorer.msn.com
RE: =
Isn't == a logical operator? I am not trying to compare the two objects. From: Sally [EMAIL PROTECTED] To: Nick Transier [EMAIL PROTECTED] Subject: RE: = Date: Thu, 21 Jun 2001 17:18:47 +0100 You should use == instead of = -Original Message- From: Nick Transier [mailto:[EMAIL PROTECTED]] Sent: 21 June 2001 17:09 To: [EMAIL PROTECTED] Subject: = I have written some OO perl and I have a problem that I just realized, when you set an object = to another object, they become irreversibly linked and all operations on one or the other causes changes in both. If I am trying to simply initialize the object and not link them, how do I get around this problem? Thanks, -Nick _ Get your FREE download of MSN Explorer at http://explorer.msn.com _ Get your FREE download of MSN Explorer at http://explorer.msn.com
Cloning
Ok, so I see the way around the = problem with cloning, however, there is a clone module on CPAN, but I have no idea how to install it using win2k. Any ideas? Thanks, -Nick _ Get your FREE download of MSN Explorer at http://explorer.msn.com
PPM
Ok, I am running windows 2000, I have perl, but I do not know which distribution, I do not think that it is activestate's however. I searched by drive and found ppm in a folder in the perl folder, but there is no executable and I do not know how to run it at the dos command line. I have downloaded a tar file of the module I want, but there is no PPD or XML file like is described in the documentation for ppm. I do have a c compiler however. Please help. Thanks, -Nick _ Get your FREE download of MSN Explorer at http://explorer.msn.com
PPM
Ok, so I was wrong, I do have ppm, but I have installed the package but it doesn't work. I installed the clone package available from Activstate, but when I say use clone in my program, it says the files are missing. What is this all about? -Nick _ Get your FREE download of MSN Explorer at http://explorer.msn.com
truncating
If I am generating a random number with the rand function, how can I truncate the resulting var to an integer? -Nick _ Get your FREE download of MSN Explorer at http://explorer.msn.com
$self def
Given this is my definition for self in some new constructor:
sub new {
$self {
Next = @[Max_Level],
}
}
First, is this the proper way to have Next be a reference to an annonymous
array of size Max_Level?
More importantly, how do you reference the elements in the array referenced
by Next?
Thanks,
-Nick
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Passing between Packages
I have two different packages that access each others methods. (where in my case one package is an element I have defined and the other package is an implementation of a list of those elements) When I call a method from package 1 with an object from package 2. the method in package 1 takes a $self var as the first parameter. This much I believe I understand...However, does that $self var then allow you to access all of the methods of it's originial package (2), or do have to make some sort of package definition? Thanks, -Nick _ Get your FREE download of MSN Explorer at http://explorer.msn.com
Re: $self def
So then would I access the nth element by
@{$self-{Next}}[n] ??
From: [EMAIL PROTECTED] (Randal L. Schwartz)
To: Nick Transier [EMAIL PROTECTED]
CC: [EMAIL PROTECTED]
Subject: Re: $self def
Date: 20 Jun 2001 09:29:41 -0700
Nick == Nick Transier [EMAIL PROTECTED] writes:
Nick Given this is my definition for self in some new constructor:
Nick sub new {
Nick$self {
Nick Next = @[Max_Level],
Nick}
Nick }
Nick First, is this the proper way to have Next be a reference to an
Nick annonymous array of size Max_Level?
No need to predeclare a size. Stop thinking Java/Fortran/C/C++.
Arrays have a size because people put things into them! Just let
it start out empty, and push @{$self-{Next}}, $new each time
you want to add one onto the end.
Nick More importantly, how do you reference the elements in the array
Nick referenced by Next?
Just think of @{$self-{Next}} as an array:
foreach my $item (@{$self-{Next}}) {
$item is one of the items
}
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[EMAIL PROTECTED] URL:http://www.stonehenge.com/merlyn/
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RE: $self def
You are saying I cannot set the size of an array? I understand that you do
not have to, but I need to in this case so that my iteration loops work
correctly.
From: John Edwards [EMAIL PROTECTED]
To: 'Nick Transier' [EMAIL PROTECTED], [EMAIL PROTECTED]
Subject: RE: $self def
Date: Wed, 20 Jun 2001 17:34:51 +0100
Are you trying to use a hash??
---
@myArray = qw(one two three four);
new;
sub new {
$self{'Next'} = \@myArray;
}
print Element 0 is $self{'Next'}-[0]\n;
---
You can't specifiy the size of the array, it's dynamic. Just enter your
data
into the array and it will change size accordingly. If you want a scalar
reference to an array use this
@myArray = qw(one two three four);
$reference = \@myArray;
print @{$reference}[0];
HTH
John
-Original Message-
From: Nick Transier [mailto:[EMAIL PROTECTED]]
Sent: 20 June 2001 17:22
To: [EMAIL PROTECTED]
Subject: $self def
Given this is my definition for self in some new constructor:
sub new {
$self {
Next = @[Max_Level],
}
}
First, is this the proper way to have Next be a reference to an annonymous
array of size Max_Level?
More importantly, how do you reference the elements in the array referenced
by Next?
Thanks,
-Nick
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Shell Program
I have written a module I want to test in a shell program, how do I load the module in another perl file to test the methods of the module's packages? -Nick _ Get your FREE download of MSN Explorer at http://explorer.msn.com
method calls outside the package
Ok, I have a package
package blah;
{
sub foo {
print I do not understand perl
return 5;
}
}
Now, how do I call this function from outside the package?
I have written this:
$perlversion = blah::-foo;
but it doesn't work, it asks for explicit package name.
Please help.
-Nick
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Re: method calls outside the package
I tried that, same error. $perlversion requires explicit package name
From: Jeff 'japhy' Pinyan [EMAIL PROTECTED]
Reply-To: [EMAIL PROTECTED]
To: Nick Transier [EMAIL PROTECTED]
CC: [EMAIL PROTECTED]
Subject: Re: method calls outside the package
Date: Wed, 20 Jun 2001 15:53:50 -0400 (EDT)
On Jun 20, Nick Transier said:
package blah;
{
sub foo {
print I do not understand perl
Missing a semicolon above...
return 5;
}
}
Now, how do I call this function from outside the package?
blah::foo() will work.
$perlversion = blah::-foo;
That works too, but kinda kruftily.
but it doesn't work, it asks for explicit package name.
That's on your variable. You need to declare it.
my $version = blah::foo();
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I am Marillion, the wielder of Ringril, known as Hesinaur, the Winter-Sun.
Are you a Monk? http://www.perlmonks.com/ http://forums.perlguru.com/
Perl Programmer at RiskMetrics Group, Inc. http://www.riskmetrics.com/
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Self Def
Given that I am trying to define an object attribute which is an array of
references to other object of the same type, how do I define this in the
$self portion of my sub new constructor? This is what I have, will this
work? Next is meant to hold an array of pointers or references.
sub new {
my $invocant = shift;
my $class = ref($invocant) || $invocant;
my $self = {
Next,
@_,
};
return bless $self,$class;
}
thanks,
-Nick
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Re: Self Def
The thing is, I want to set the array reference later and not when the
object is being created.
From: [EMAIL PROTECTED] (Randal L. Schwartz)
To: Nick Transier [EMAIL PROTECTED]
CC: [EMAIL PROTECTED]
Subject: Re: Self Def
Date: 19 Jun 2001 14:12:13 -0700
Nick == Nick Transier [EMAIL PROTECTED] writes:
Nick Given that I am trying to define an object attribute which is an
array
Nick of references to other object of the same type, how do I define this
Nick in the $self portion of my sub new constructor? This is what I have,
Nick will this work? Next is meant to hold an array of pointers or
Nick references.
Nick sub new {
Nick my $invocant = shift;
Nick my $class = ref($invocant) || $invocant;
Nick my $self = {
Nick Next,
Nick @_,
Nick };
Nick return bless $self,$class;
Nick }
You need an array ref there, not an array. Simplest would be a
shallow copy of the invocation list.
sub new {
my $class = shift; # do NOT use the ref() garbage, please
my $self = { Next = [@_] };
bless $self, $class;
}
You might be able to get away with \@_ in place of [@_], but I know
this is safer. :)
See perldoc perlboot for more details.
--
Randal L. Schwartz - Stonehenge Consulting Services, Inc. - +1 503 777 0095
[EMAIL PROTECTED] URL:http://www.stonehenge.com/merlyn/
Perl/Unix/security consulting, Technical writing, Comedy, etc. etc.
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scope
If I define a function just in the freespace of a file and have included in
that file two packages which are bracketed in like:
sub function {}
package 1;
{}
package 2;
{}
How do I access the function (make a function call) from within one of the
packages?
is it main::function or is it something else.
Also, is it ok to call functions which take no parameters as just the
function name. like $var = function; as opposed to $var = function();
Thanks,
-Nick
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Sub Calls
Assuming I am defining an object which has as its only property a level
associated with it, would these be the correct simple subroutines to
retrieve and set that property. Also, is this the correct usage of the @_
array such that the level value would be 999 unless I called new(Level =
something else)
sub new {
my $invocant = shift;
my $class = ref($invocant) || $invocant;
my $self = {
Level = 999,
@_,
};
return bless $self,$class;
}
sub getlevel {
return $$self{Level};
}
sub setlevel {
$$self{Level} = shift(@_);
}
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class stuff
Given this function to create a new class object:
sub new {
my $invocant = shift;
my $class = ref($invocant) || $invocant;
my $self = {
Level = 999, #values Value = 999,
Key = 999,
@Next, #array of pointers to next elements
@_,
};
return bless $self,$class;
}
Can you define an array of pointers (@Next) and leave it with nothing in it
at declaration? If so -
Is this the proper way to access a class object's Next array at the
$level'th level?
$self-{Next[$level]}
thanks,
-Nick
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more class stuff
given this new function which acts as a constructor
sub new {
my $invocant = shift;
my $class = ref($invocant) || $invocant;
my $self = {
Level = 999,
Value = 999,
Key = 999,
@Next,
@_,
};
return bless $self,$class;
}
I am getting the following error:
Global symbol @Next requires explicit package name at c:\
What does this mean?
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Re: more class stuff
@Next will become a class (or package) variable, but it is not set yet
because I have another function which does that after the object is created.
It is meant to be an array of pointers or references I guess. Is there
anything I can do to quell the error messages without wrongly initializing
the var?
From: Chas Owens [EMAIL PROTECTED]
To: [EMAIL PROTECTED]
Subject: Re: more class stuff
Date: 18 Jun 2001 17:57:14 -0400
On 18 Jun 2001 16:42:45 -0500, Nick Transier wrote:
given this new function which acts as a constructor
sub new {
my $invocant = shift;
my $class = ref($invocant) || $invocant;
my $self = {
Level = 999,
Value = 999,
Key = 999,
@Next,
@_,
};
return bless $self,$class;
}
I am getting the following error:
Global symbol @Next requires explicit package name at c:\
What does this mean?
snip /
It means you are using strict and it is warning you that you have not
created @Next. Where is @Next comming from? Is it a class variable?
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Packages
Do you have to end packages with any type of notation or command? I have written a module file with two packages in it, but I am having a hell of a time with miss-referenced or no reference vars in the file. Thanks, -Nick _ Get your FREE download of MSN Explorer at http://explorer.msn.com
