This is really more of a question of how to pass a variable to a sub. First
off, check out perldoc perlsub. To avoid problems like this, 'use strict'
whenever possible at the top of your scripts.
Anyway, here's how to fix this:
Passing a variable to a sub: All variables passed to subs are put into the
@_ array and then passed. Thus, when you do a printStatement($var), the
contents of $var are passed to the first element of the @_ array. In the
sub in your module, there is no such thing as the variable $var. If you had
used 'use strict', you would have generated an error. So what you need to
do is change your module as follows:
########################
#!/usr/bin/perl
use strict;
package HelloWorld;
require Exporter;
our @ISA = qw(Exporter);
our @EXPORT = qw(printStatement);
our $VERSION = 1.00;
sub printStatement { print $_[0] }
1;
########################
One small problem that this prestents is that you can not pass more than one
array to a subroutine. If you do, then they will both be stuck together in
the @_ array. That is where you start getting into references.
Some suggested reading:
perldoc perlsub
perldoc perllol
perldoc -f my
perldoc -f our
There is an article out there on the Web called "Coping with Scoping". I
really recommend everyone read it.
-----Original Message-----
From: jeff [mailto:[EMAIL PROTECTED]]
Sent: Tuesday, October 15, 2002 4:30 PM
To: [EMAIL PROTECTED]
Subject: passing a variable to a module
Quick question. I want to pass a variable to a non-oo module that I
created. But I how do I get the module to contain the value of the
variable that was created in the 'main' namespace. I think there is
something easy that I am not understanding. Example code below.
PROGRAM BEGIN
#!/usr/bin/perl
use HelloWorld;
$var = 'hello world';
printStatement;
exit;
PROGRAM END
MODULE BEGIN
#!/usr/bin/perl
package HelloWorld;
require Exporter;
our @ISA = qw(Exporter);
our @EXPORT = qw(printStatement);
our $VERSION = 1.00;
sub printStatement { print $var; }
1;
MODULE END
THINGS I'VE TRIED BEGIN
I've tried passing in $var to printStatement,
printStatement($var)
in the program
I've tried using the 'main' namespace in the module
print $main::var;
I've tried passing a reference the $var in the module
printStatement (\$var);
THINGS I'VE TRIED END
Executive summary: how do I define a variable in my program and have a
module use that variable definition (in a non-oo module).
Jeff
--
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]
--
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]
