Changing Module Tree

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

Hey, monks. I've got two module trees which are nearly identical, and I have to run the same command once with each of these trees. The best method I can come up with is to combine a local $ENV{PERL5LIB} with system:

#/usr/bin/perl

for my $tree ("a","b") {
    local $ENV{PERL5LIB} = $tree;
    system("perl -e 'use Foo;Foo::Bar()'");
}
[download]

Is there a way to accomplish this without having to start a subprocess?

Comment on Changing Module Tree Download Code

Replies are listed 'Best First'.
Re: Changing Module Tree by wind (Priest) on Apr 05, 2011 at 20:28 UTC
`#/usr/bin/perl use strict; use warnings; for my $tree ("a","b") { local $ENV{PERL5LIB} = $tree; delete $INC{'Foo.pm'}; require Foo; Foo::Bar(); }` [download] As demonstrated by GrandFather recently in Re: Adding code to a Perl program without stopping it.	[reply] [d/l]
Re^2: Changing Module Tree by lackita (Sexton) on Apr 05, 2011 at 21:09 UTC
Alright, so that solves the problem of a single module, but what if Foo uses several other modules? Also, this would work in the limited example, but I also have a third module path that will need to be restored afterwards: `#/usr/bin/perl use Foo; Foo::Prep(); for my $tree ("a","b") { local $ENV{PERL5LIB} = $tree; delete $INC{'Foo.pm'}; require Foo; Foo::Bar(); } Foo::Cleanup();` [download] It seems cumbersome to have to stick an additional delete/require after the loop.	[reply] [d/l]
Re^3: Changing Module Tree by wind (Priest) on Apr 05, 2011 at 21:25 UTC
Save the state of the `%INC` before the loop, and restore it at the beginning of each iteration. Something as simple as this might work, assuming `%INC` isn't a tied hash: `%INC = %old_INC;` [download] Or alternatively: `for (keys %INC) { delete $INC{$_} if ! $old_INC{$_}; }` [download]	[reply] [d/l] [select]
Re^4: Changing Module Tree by lackita (Sexton) on Apr 06, 2011 at 14:21 UTC
Re^5: Changing Module Tree by Anonymous Monk on Apr 06, 2011 at 14:44 UTC
Re^5: Changing Module Tree by wind (Priest) on Apr 06, 2011 at 22:50 UTC