NAME

Sub::AliasedUnderscore - transform a subroutine that operates on $_ into one that operates on $_[0]

SYNOPSIS

            

              
              
use Sub::AliasedUnderscore qw/transform transformed/;
my $increment = sub { $_++ };
$increment = transform $increment;
$_ = 1; 
my $a = 41;
$increment->($a); # returns 41
# $a is now 42; $_ is still 1
my $decrement = transformed { $_-- };
$decrement->($a);
# $a is now 41; $_ is still 1
            
          

DESCRIPTION

Often you'll want to accept a subroutine that operates on $_, like map and grep do. The details of getting $_ to work that way are inconvenient to worry about every time, so this module abstracts that away. Transform the subroutine that touches $_ with transform, and then treat it as though it is operating on $_[0].

EXPORT

Nothing by default. If you want transform or transformed, request them in the import list.

FUNCTIONS

transform($sub)

Transforms $sub to modify $_[0] instead of $_.

This means you can write your subroutine as though it were the first argument of map or grep, but execute it like $sub-($arg)>.

Everything works exactly the same as map or grep -- $_ is localized, but aliased to whatever you call the subroutine with. That means that modifying $_ in $sub will modify the argument passed to the transformed sub, but won't touch the $_ that already exists.

It makes $_ DWIM.

transformed BLOCK

Like transform, but accepts a code block instead of a coderef:

            

              
              
my $sub = transformed { do something to $_ }
$sub->($a); # $a is $_ in the above block
            
          

BUGS

None known; report to RT.

CODE

The repository is managed by git. You can clone the repository with:

            

              
              
git clone git://git.jrock.us/Sub-AliasedUnderscore
            
          

Patches welcome!

AUTHOR

Jonathan Rockway jrockway@cpan.org

LICENSE

Copyright (c) 2007 Jonathan Rockway. You may use, modify, and distribute this code under the same conditions as Perl itself.