searching global variables

[Kiss Gabor]

I have need a code snippet those input is a text of a perl subroutine
(e.g. coming from a file) and the output of list of global variables
used by the sub.
So far I created something like this:

-------------8<-------------------8<------------------
# $code holds the source of subroutine. E.g.:
$code = q{ sub { my $aaa = $bbb + $ccc; return $aaa; } };

my %vars;
open(PARSER,q{perl -c -e 'use strict; }.$code.q{' 2>&1 |}) or die;
while (<PARSER>) {
next unless /Global symbol "\$(\w+)" requires explicit package name at/;
$vars{$1}++;
}
close PARSER;

my $varlist;
foreach (keys %vars) {
$varlist .= qq{our \$$_; };
}

# In the second pass globals do not cause error.
# Let's see if syntax is correct otherwise.
open(PARSER,q{perl -c -e 'use strict; }.$varlist.$code.q{' 2>&1 |}) or die;
while (<PARSER>) {
# check other errors or '-e syntax OK' message
}
close PARSER;

# Global variables are keys of %vars (I.e. 'bbb' and 'ccc')
-------------8<-------------------------8<------------------

However this is not an elegant solution. I wonder if there is any way
to omit one or both fork+exec.

Any hints will be appreciated.

Gabor

 

[sln]

I have need a code snippet those input is a text of a perl subroutine
(e.g. coming from a file) and the output of list of global variables
used by the sub.
So far I created something like this:

-------------8<-------------------8<------------------
# $code holds the source of subroutine. E.g.:
$code = q{ sub { my $aaa = $bbb + $ccc; return $aaa; } };

my %vars;
open(PARSER,q{perl -c -e 'use strict; }.$code.q{' 2>&1 |}) or die;
while (<PARSER>) {
next unless /Global symbol "\$(\w+)" requires explicit package name at/;
$vars{$1}++;
}
close PARSER;

my $varlist;
foreach (keys %vars) {
$varlist .= qq{our \$$_; };
}

# In the second pass globals do not cause error.
# Let's see if syntax is correct otherwise.
open(PARSER,q{perl -c -e 'use strict; }.$varlist.$code.q{' 2>&1 |}) or die;
while (<PARSER>) {
# check other errors or '-e syntax OK' message
}
close PARSER;

# Global variables are keys of %vars (I.e. 'bbb' and 'ccc')
-------------8<-------------------------8<------------------

However this is not an elegant solution. I wonder if there is any way
to omit one or both fork+exec.

Any hints will be appreciated.

Gabor

If the object of an open is an expression, then sure why not?

sln

===================

sub { my $aaa = $bbb + $ccc; return $aaa; }

open(PARSER,perl -c -e 'use strict; sub { my $aaa = $bbb + $ccc; return $aaa; }
' 2>&1 |) or die;

our $VARS;

open(PARSER,perl -c -e 'use strict; VARLIST sub { my $aaa = $bbb + $ccc; return
$aaa; } ' 2>&1 |) or die;