signatures(3pm) 					User Contributed Perl Documentation					   signatures(3pm)

NAME

       signatures - subroutine signatures with no source filter

SYNOPSIS

	   use signatures;

	   sub foo ($bar, $baz) {
	       return $bar + $baz;
	   }

DESCRIPTION

       With this module, we can specify subroutine signatures and have variables automatically defined within the subroutine.

       For example, you can write

	   sub square ($num) {
	       return $num * $num;
	   }

       and it will be automatically turned into the following at compile time:

	   sub square {
	       my ($num) = @_;
	       return $num * $num;
	   }

       Note that, although the syntax is very similar, the signatures provided by this module are not to be confused with the prototypes described
       in perlsub. All this module does is extracting items of @_ and assigning them to the variables in the parameter list. No argument
       validation is done at runtime.

       The signature definition needs to be on a single line only.

       If you want to combine sub signatures with regular prototypes a "proto" attribute exists:

	   sub foo ($bar, $baz) : proto($$) { ... }

METHODS

       If you want subroutine signatures doing something that this module doesn't provide, like argument validation, typechecking and similar, you
       can subclass it and override the following methods.

   proto_unwrap ($prototype)
       Turns the extracted $prototype into code.

       The default implementation returns "my (${prototype}) = @_;" or an empty string, if no prototype is given.

   inject ($offset, $code)
       Inserts a $code string into the line perl currently parses at the given $offset. This is only called by the "callback" method.

   callback ($offset, $prototype)
       This gets called as soon as a sub definition with a prototype is encountered. Arguments are the $offset within the current line perl is
       parsing and extracted $prototype.

       The default implementation calls "proto_unwrap" with the prototype and passes the returned value and the offset to "inject".

BUGS

       prototypes aren't checked for validity yet
	   You won't get a warning for invalid prototypes using the "proto" attribute, like you normally would with warnings enabled.

       you shouldn't alter $SIG{__WARN__} at compile time
	   After this module is loaded you shouldn't make any changes to $SIG{__WARN__} during compile time. Changing it before the module is
	   loaded or at runtime is fine.

SEE ALSO

       Method::Signatures

       MooseX::Method::Signatures

       Sub::Signatures

       Attribute::Signature

       Perl6::Subs

       Perl6::Parameters

AUTHOR

       Florian Ragwitz <rafl@debian.org>

THANKS

       Moritz Lenz and Steffen Schwigon for documentation review and improvement.

COPYRIGHT AND LICENSE

       Copyright (c) 2008  Florian Ragwitz

       This module is free software.

       You may distribute it under the same license as Perl itself.

perl v5.14.2							    2009-07-31							   signatures(3pm)