Re: Your named arguments

Personally, I never really cared about fancy prototype handling. I just:

my ($this, $a, $b) = @_;
[download]

in my code. When doing named params, I will normally do something like %h and then immediately convert then into specific vars.

My reason for posting was I saw your example:

sub convert (:$from, :$to, :$thing) { ... }
[download]

It occurred to me that it would be rather easy to support such a thing WIHTOUT sourcefilters thanks to the prototype function.

There are dozens of potential impls. using prototype and I will leave that as an excersize to the readers. But, I don't think I have ever seen a module that does that without source filters. Then again, I haven't looked very hard.

Update: Working on an example of said package.

Update: Here is a quicky that I through together. I have to go home, so I can't spend too much time on this, but I can see why no one has done this before. The code I wrote is:

package Signatures;

sub import {
    no warnings;
    no strict;
    my $package = caller;
    for (keys %{ $package . '::' }) {
        next unless exists &{ $package . "::$_" };
        my $sub = \ &{ $package . "::$_" };
        next unless my $proto = prototype $sub;
        *{ $package . "::$_" } = eval qq {
            sub { 
                package $package; 
                local ($proto) = \@_; 
                \$sub->() 
            }
        }
    }
}
[download]

Before you kill me, please understand that this was written in 10 minutes and is not intended to be used by anyone. That is why there is no "use strict" and "use warnings", etc. :-) There were several major problems I encountered.

The use Signatures has to occurr after all sub declarations in the calling module. I can't think of a way around that at the moment.
The params had to be localized in this approach. Lexacalizing them would be much much better.

Anyway, here is the code I was able to run. It does work, but I didn't really test this mess.

#!perl -l

foo("aaaa", "bbb");

sub foo ($a, $b) { print $a; print $b }

use Signatures;
[download]

Well, it was an interesting idea, but I don't know if it can really go anywhere. I'll think more about it tonight.

Ted Young

($$<<$$=>$$<=>$$<=$$>>$$) always returns 1. :-)

Comment on Re: Your named arguments Select or Download Code

Replies are listed 'Best First'.

Re^2: Your named arguments
by Jenda (Abbot) on Nov 08, 2005 at 17:51 UTC

It's not hard to modify it so that the location of the use statement doesn't matter:

package Signatures;

my @packages;

sub import {
    my $package = caller;
    push @packages, $package;
}

INIT {
    for my $package (@packages) {
        no warnings;
        no strict;
        for (keys %{ $package . '::' }) {
            next unless exists &{ $package . "::$_" };
            my $sub = \&{ $package . "::$_" };
            next unless my $proto = prototype $sub;
            eval qq {
                package $package;
                sub $_ {
                    local ($proto) = \@_;
                    \$sub->()
                }
            }
        }
    }
}

1;
[download]

Jenda
XML sucks. Badly. SOAP on the other hand is the most powerfull vacuum pump ever invented.

[reply]
[d/l]