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

I am trying to invoke a subroutine of a particular perl module and passing an argument as well ,where the subroutine ,the perl module and the argument are parsed from a xml file, but everytime the passed argument in the invoked subroutine gets the name of the perl module..pls help me out i am providing the code below 

use NAS;
use RRC;
use Layer1;
use Cwd;
use XML::Simple;
use Data::Dumper;
$xml = new XML::Simple (KeyAttr=>[]);# read XML file
$config =$xml->XMLin("Config_test.xml");
$top = $config->{ConfigRoot};
$start =$top->{debugDef};
$begin =$start->{general};
open report,">report.txt";
foreach my $var(@{$begin->{genCategory1}}){
print report $var->{sysTag},"\n\n\n";
$str=$var->{pm};
foreach my $var1(@{$var->{genCategory2}}){
print report $var1->{name},"\n\n";
$str1=$var1->{subroutine};
$regexp=$var1->{searchStr};
print $regexp,"\n";
$str->$str1($regexp);

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where NAS,RRC and Layer1 are the name of the perl modules,the line $str->$str1($regexp); always passes $str as parameter to the subroutine..

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Re: invoking subroutines
by syphilis (Archbishop) on Jul 01, 2011 at 01:04 UTC
    always passes $str as parameter to the subroutine..

    Yes - $str is the *second* argument that gets passed. The first argument will be the package name. Here's a demo: 
    use warnings;
use strict;
package MY_FOO;

my $str = 'this is the second argument';
MY_FOO->foo($str);


sub foo {
    print "$_\n" for @_;
}

__END__
prints:

MY_FOO
this is the second argument

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    (I haven't dug into your code - I'm merely guessing that this is what's happening.)

    Cheers,
    Rob
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Re: invoking subroutines
by ig (Vicar) on Jul 01, 2011 at 07:19 UTC
    the line $str->$str1($regexp); always passes $str as parameter to the subroutine.

    $str is passed as first argument to the subroutine because you are using method invocation syntax. In particular, you are using the arrow operator: ->.

    If you don't want $str passed as the first argument, you could use a symbolic reference:&{"${str}::${str1}"}($regexp).

    use strict;
use warnings;

package XXX;

sub YYY {
    my ($x) = @_;
    print "hi there $x\n";
}

package main;

my $str = 'XXX';
my $str1 = 'YYY';

{
    no strict "refs";
    &{"${str}::${str1}"}(10);
}

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