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.