/ 
Sub-Prototype-Util-0.08
River stage one • 1 direct dependent • 1 total dependent
/ Sub::Prototype::Util

NAME

Sub::Prototype::Util - Prototype-related utility routines.

VERSION

Version 0.08

SYNOPSIS

use Sub::Prototype::Util qw/flatten recall wrap/;

my @a = qw/a b c/;
my @args = ( \@a, 1, { d => 2 }, undef, 3 );

my @flat = flatten '\@$;$', @args; # ('a', 'b', 'c', 1, { d => 2 })
recall 'CORE::push', @args; # @a contains 'a', 'b', 'c', 1, { d => 2 }, undef, 3
my $splice = wrap 'CORE::splice', compile => 1;
my @b = $splice->(\@a, 4, 2); # @a is now ('a', 'b', 'c', 1, 3) and @b is ({ d => 2 }, undef)

DESCRIPTION

Prototypes are evil, but sometimes you just have to bear with them, especially when messing with core functions. This module provides several utilities aimed at facilitating "overloading" of prototyped functions.

They all handle 5.10's _ prototype.

FUNCTIONS

flatten $proto, @args

Flattens the array @args according to the prototype $proto. When @args is what @_ is after calling a subroutine with prototype $proto, flatten returns the list of what @_ would have been if there were no prototype.

recall $name, @args

Calls the function $name with the prototyped argument list @args. That is, @args should be what @_ is when you define a subroutine with the same prototype as $name. For example,

my $a = [ ];
recall 'CORE::push', $a, 1, 2, 3;

will call push @$a, 1, 2, 3 and so fill the arrayref $a with 1, 2, 3. This is especially needed for core functions because you can't goto into them.

You can also force the use of a specific prototype. In this case, $name must be a hash reference that holds exactly one key/value pair, the key being the function name and the value the prototpye that should be used to call it.

recall { 'CORE::push' => '\@$' }, $a, 1, 2, 3; # will only push 1

This allows you to recall into CORE::grep and CORE::map by using the \&@ prototype :

sub mygrep (&@) { recall { 'CORE::grep' => '\&@' }, @_ } # the prototypes are intentionally different

wrap $name, %opts

Generates a wrapper that does the same thing as "recall", but specialized for a given function. This wrapper can be compiled once for all to avoid calling eval at each run (like "recall" does). You can still force the prototype by passing { $name => $proto } as the first argument. Others arguments are seen as key / value pairs and tune the code generated by "wrap". Valid keys are :

ref => $func

Specifies the function used in the generated code to test the reference type of scalars. Defaults to 'ref'. You may also want to use Scalar::Util::reftype.

wrong_ref => $code

The code executed when a reference of incorrect type is encountered. The result of this snippet is also the result of the generated code, hence it defaults to 'undef'. It's a good place to croak or die too.

sub => $bool

Encloses the code into a sub { } block. Default is true.

compile => $bool

Makes "wrap" compile the code generated and return the resulting code reference. Implies sub => 1. Be careful that in this case ref must be a fully qualified function name. Defaults to false.

This is how you make your own push that pushes into array references :

my @a = (0 .. 2);
my $push = wrap 'CORE::push', compile => 1;
$push->(\@a, 3 .. 7); # returns 3 + 5 = 8, and @a now contains 0 .. 7

EXPORT

The functions "flatten", "recall" and "wrap" are only exported on request, either by providing their name or by the ':funcs' and ':all' tags.

DEPENDENCIES

Carp, Exporter (core modules since perl 5), Scalar::Util (since 5.7.3).

AUTHOR

Vincent Pit, <perl at profvince.com>, http://www.profvince.com.

You can contact me by mail or on #perl @ FreeNode (vincent or Prof_Vince).

BUGS

Please report any bugs or feature requests to bug-sub-prototype-util at rt.cpan.org, or through the web interface at http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Sub-Prototype-Util. I will be notified, and then you'll automatically be notified of progress on your bug as I make changes.

SUPPORT

You can find documentation for this module with the perldoc command.

perldoc Sub::Prototype::Util

Tests code coverage report is available at http://www.profvince.com/perl/cover/Sub-Prototype-Util.

COPYRIGHT & LICENSE

Copyright 2008 Vincent Pit, all rights reserved.

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.