This and other RFCs are available on the web at http://dev.perl.org/rfc/ =head1 TITLE Make subroutines' prototypes accessible from Perl =head1 VERSION Maintainer: Simon Cozens <[EMAIL PROTECTED]> Date: 25 Sep 2000 Mailing List: [EMAIL PROTECTED] Number: 298 Version: 1 Status: Developing =head1 ABSTRACT Allow sub prototypes to be got and set by Perl at compile time. =head1 DESCRIPTION The motivation behind this RFC is to allow subroutine attributes to define canned "prototype classes". As a very trivial example: use attributes::prototype 'a_and_b' => "($a,$b)" sub foo : a_and_b { # $a and $b are here set to what we knew as $_[0] and $_[1] } Now, yes, I am suggesting that there be a C<attributes::prototype> pragma, but that's not the thrust of my RFC - the point is how you implement it, and you have to do this by making the prototype available. That's the motivation; the justification is slightly different, and it's to increase the flexibility and the possibilities for introspection that Perl 6's subroutines provide the user. More flexibility is always a good thing. =head1 IMPLEMENTATION There are a number of ways that this can be done; I'd originally thought that there should be Yet Another Special Variable, but it seems more Perlish to change C<prototype> to be a function which returns the prototype of a built-in (same as Perl 5) or, when passed a fully qualified sub name, an lvaluable subroutine to get or set the prototype of that sub. So C<attributes::prototype> can then be implemented something vaguely like this: store "prototype class" declarations in a hash, say, C<%PROTOS>; register the new attributes; when the attribute is processed, set C<prototype($sub) = $PROTOS{$attr}>. =head1 REFERENCES RFC 57: Subroutine prototypes and parameters
