defining functions at runtime

batkins has asked for the wisdom of the Perl Monks concerning the following question:

Hi. I'm trying to define two functions differently depending on the user's OS. My code currently looks like this:

package XAMP;

use strict;
use warnings;

use Milkbone;

my $commit = 0;
my $last_text;

#
# Some rather kludgy OS-specific code follows
#


if($^O =~ /Win32/)
{
    eval '
    package XAMP;

        use Win32::GuiText qw(FindWindowLike GetWindowText);

        sub get_text
        {
    }
    ';
}
else
{
    eval "
        use Xmms::Remote;

    my $rem = Xmms::Remote->new;
    
    sub get_text
    {
        my $text = $rem->get_playlist_title($rem->get_playlist_pos);
        $commit = 1 if $text ne $last_text;
        $last_text = $text;
        return $text;
    }
    " or die $@;
}
        return $text;
    }
    " or die $@;
}

# and then the code continues and later makes use of get_text()
[download]

But the problem is that running this gives me errors like:

Couldn't require XAMP.pl for XAMP:  Global symbol "$rem" requires expl
+icit package name at plugins/XAMP.pl line 30.
Global symbol "$text" requires explicit package name at plugins/XAMP.p
+l line 30.Global symbol "$rem" requires explicit package name at plug
+ins/XAMP.pl line 30.
Global symbol "$rem" requires explicit package name at plugins/XAMP.pl
+ line 30.
Global symbol "$text" requires explicit package name at plugins/XAMP.p
+l line 30.Global symbol "$text" requires explicit package name at plu
+gins/XAMP.pl line 30.Global symbol "$text" requires explicit package 
+name at plugins/XAMP.pl line 30.Compilation failed in require at (eva
+l 26) line 1.
        main::main() called at /home/bill/milkbone/mos.pl line 64
[download]

Any idea why this happens?

TIA,
Bill

milkbone - perl/tk instant messaging - it's the only way to fly

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Replies are listed 'Best First'.
Re: defining functions at runtime by Paladin (Vicar) on Jun 20, 2003 at 04:45 UTC
In your second `eval` you are using double quotes (`"`). In a double quoted string, variables interpolate. Since you are using `strict` the vars in that double quoted string need to be declared. Although, I am guessing from the code that you actually want single quotes, just like your first `eval`.	[reply] [d/l] [select]
Re: Re: defining functions at runtime by batkins (Chaplain) on Jun 20, 2003 at 10:25 UTC
Oh wow. Now I feel like an idiot. :) Thanks, though! milkbone - perl/tk instant messaging - it's the only way to fly	[reply]
Re: defining functions at runtime by gellyfish (Monsignor) on Jun 20, 2003 at 08:48 UTC
Paladin is probably right about the quotes. On a more general note, rather than using the eval to create the sub on the fly you might consider assigning a CODEREF to the 'get_text' typeglob: `get_text = sub { # ... };` [download] This is possibly a little clearer than the 'eval' ins some cases. /J\	[reply] [d/l]