Re: use of require causing name space problems?
Ok, I entirely retract my post to which this is a reply. Hey, I've been up all night. If the scripts are running as separate processes, then, well, I don't know. > Does anyone know why perl behaves like this? [see earlier posts in thread]
RE: use of require causing name space problems?
Does anyone know why perl behaves like this? It seems to me
that since the scripts are running as seperate processes, there
should not be a problem.
The only information Ive found on the subject is this:
require - the file being required inserts the subroutine names
into a package ( a namespace ) of its own choosing, not
your package. Second, require happens at run-time, so
the decleration occurs to late to serve as a declaration
in the file invoking the require.
use - performs a require at compile time, then lets you import
declerations into your own namespace.
Would it behoove me to modify my library to be a perl module and
switch require to use? Would this solve my problem?
thanks
rodney
> -Original Message-
> From: Me [mailto:[EMAIL PROTECTED]]
> Sent: Thursday, June 21, 2001 9:23 AM
> To: Rodney Holm; [EMAIL PROTECTED]
> Subject: Re: use of require causing name space problems?
>
>
> > sub WriteFile
> > {
> > my ($file,@lines) = @_;
> > my ($line);
> >
> > open(FILE,">$file");
>
> FILE is a problem.
>
> If you are using perl 5.6 or later, you can do:
>
> my $fh;
>
> and then use $fh where you were using FILE, eg
>
> open($fh, ">$file");
>
> If you aren't using 5.6, it gets more complicated
> and I'm out of, er, my depth. I'll post later if I see
> what to do, but I suggest you post again and ask.
>
> > foreach $line (@lines)
>
> $line is a problem.
>
> Fixing $line is easy. I'll let you guess. :>
> Ok, no I won't:
>
> foreach my $line (@lines)
>
> > {
> > print FILE $line; }
> > }
> > close(FILE);
> > return(0);
> > }
> > open(FILE,">$file");
>
>
Re: use of require causing name space problems?
> sub WriteFile
> {
> my ($file,@lines) = @_;
> my ($line);
>
> open(FILE,">$file");
FILE is a problem.
If you are using perl 5.6 or later, you can do:
my $fh;
and then use $fh where you were using FILE, eg
open($fh, ">$file");
If you aren't using 5.6, it gets more complicated
and I'm out of, er, my depth. I'll post later if I see
what to do, but I suggest you post again and ask.
> foreach $line (@lines)
$line is a problem.
Fixing $line is easy. I'll let you guess. :>
Ok, no I won't:
foreach my $line (@lines)
> {
> print FILE $line; }
> }
> close(FILE);
> return(0);
> }
> open(FILE,">$file");
RE: use of require causing name space problems?
## somewhat simplified version of the WriteFile sub
sub WriteFile
{
my ($file,@lines) = @_;
my ($line);
open(FILE,">$file");
foreach $line (@lines)
{
print FILE $line; }
}
close(FILE);
return(0);
}
> -Original Message-
> From: Me [mailto:[EMAIL PROTECTED]]
> Sent: Thursday, June 21, 2001 8:45 AM
> To: Rodney Holm; [EMAIL PROTECTED]
> Subject: Re: use of require causing name space problems?
>
>
> You need to make sure that variables in the called perl
> code are unique to each instance of a call. (Sorry if that
> was already obvious to you.)
>
> I suggest you post the WriteFile code and we go from there.
>
> > I have a few functions that are common to many different
> > perl applications. All of these functions live in one
> > file.
> >
> > I have many perl programs that run from cron that make
> > use of these functions. So, in each of these programs
> > I use require to gain access to these functions.
> >
> > Example:
> >
> > <<<<< doit.pl >>>>>
> > #!/usr/bin/perl
> > require '/usr/local/myperllib.pl';
> > @array = ("one\n", "two\n", "three\n");
> > ## calling WriteFile from myperllib.pl
> > WriteFile('/path/filename', @array);
> > exit;
> > <<<<< doit.pl >>>>>
> >
> > <<<<< doit1.pl >>>>>
> > require '/usr/local/myperllib.pl';
> > @array = ("four\n", "five\n", "six\n");
> > ## calling WriteFile from myperllib.pl
> > WriteFile('/path/filename1', @array);
> > exit;
> >
> > imagine many of these doit.pl scripts ( doit1.pl, doit2.pl ... ), all
> using
> > require, all calling WriteFile, all running at the same time.
> >
> > What happens is sometimes, what should end up in one file, ends up in
> > another file. I would expect:
> > $ cat /path/filename
> > one
> > two
> > three
> >
> > what I sometimes get is the contents of /path/filename1 ending up in
> > /path/filename
> > $ cat /path/filename
> > four
> > five
> > six
> >
> > How would I code my library correctly to avoid this type of namespace
> > pollution?
> >
> > thanks
> > rodney
>
>
Re: use of require causing name space problems?
You need to make sure that variables in the called perl
code are unique to each instance of a call. (Sorry if that
was already obvious to you.)
I suggest you post the WriteFile code and we go from there.
> I have a few functions that are common to many different
> perl applications. All of these functions live in one
> file.
>
> I have many perl programs that run from cron that make
> use of these functions. So, in each of these programs
> I use require to gain access to these functions.
>
> Example:
>
> < doit.pl >
> #!/usr/bin/perl
> require '/usr/local/myperllib.pl';
> @array = ("one\n", "two\n", "three\n");
> ## calling WriteFile from myperllib.pl
> WriteFile('/path/filename', @array);
> exit;
> < doit.pl >
>
> < doit1.pl >
> require '/usr/local/myperllib.pl';
> @array = ("four\n", "five\n", "six\n");
> ## calling WriteFile from myperllib.pl
> WriteFile('/path/filename1', @array);
> exit;
>
> imagine many of these doit.pl scripts ( doit1.pl, doit2.pl ... ), all
using
> require, all calling WriteFile, all running at the same time.
>
> What happens is sometimes, what should end up in one file, ends up in
> another file. I would expect:
> $ cat /path/filename
> one
> two
> three
>
> what I sometimes get is the contents of /path/filename1 ending up in
> /path/filename
> $ cat /path/filename
> four
> five
> six
>
> How would I code my library correctly to avoid this type of namespace
> pollution?
>
> thanks
> rodney
use of require causing name space problems?
I have a few functions that are common to many different
perl applications. All of these functions live in one
file.
I have many perl programs that run from cron that make
use of these functions. So, in each of these programs
I use require to gain access to these functions.
Example:
< doit.pl >
#!/usr/bin/perl
require '/usr/local/myperllib.pl';
@array = ("one\n", "two\n", "three\n");
## calling WriteFile from myperllib.pl
WriteFile('/path/filename', @array);
exit;
< doit.pl >
< doit1.pl >
require '/usr/local/myperllib.pl';
@array = ("four\n", "five\n", "six\n");
## calling WriteFile from myperllib.pl
WriteFile('/path/filename1', @array);
exit;
imagine many of these doit.pl scripts ( doit1.pl, doit2.pl ... ), all using
require, all calling WriteFile, all running at the same time.
What happens is sometimes, what should end up in one file, ends up in
another file. I would expect:
$ cat /path/filename
one
two
three
what I sometimes get is the contents of /path/filename1 ending up in
/path/filename
$ cat /path/filename
four
five
six
How would I code my library correctly to avoid this type of namespace
pollution?
thanks
rodney
