A module to merge packages

dakkar has asked for the wisdom of the Perl Monks concerning the following question:

I just wrote this little module. The problem it tries to solve is the following.

I have a set of packages, each of which specifies a part of the behaviour I need. The idea is to be able to exchange one specification with another (for those who know, I'm translating an ASM specification).

I wrote the subs in the packages to be used as methods, and one of the packages defines new, but this is not really relevant...

What I can do is something like:

 package a;
 sub sa { return 1 }
 sub sb { return 2 }

 package b;
 sub sb { return 3 }

 package main;
 use Class::Merge qw(b a) => 'c';

 $r= c->sb();  # returns 3
[download]

This, coupled with NEXT, gets me the result I need.

Now I ask:

Is this useful to anybody else?
Might it be worthy of CPAN?
I currently call it Class::Merge, but since it doesn't really involve classes, what could be a better name?

Oh, the whole module boils down to:

sub import {
  my $dest=pop;
  shift;
  eval <<"EOF";
package $dest;
\@${dest}::ISA=qw(@_);
EOF
}
[download]

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(tye)Re: A module to merge packages by tye (Sage) on Jun 26, 2002 at 14:18 UTC
Does your module boil down to more than the following? `@c::ISA= qw( b a );` If not, perhaps a more thorough description is in order. - tye (but my friends call me "Tye")	[reply] [d/l]
Re: A module to merge packages by dakkar (Hermit) on Jun 26, 2002 at 15:36 UTC
Actually, no. It's just a fancy way to set that `@ISA`.	[reply]
•Re: A module to merge packages by merlyn (Sage) on Jun 26, 2002 at 15:37 UTC
Ya know, instead of: `use Class::Merge qw(b a) => 'c';` [download] I'd just as soon write: `@C::ISA = qw(b a);` [download] as it is shorter and clearer, and doesn't require me to install a separate module. And it's "use strict" savvy. {grin} -- Randal L. Schwartz, Perl hacker	[reply] [d/l] [select]
Re: A module to merge packages by janx (Monk) on Jun 26, 2002 at 13:42 UTC
Actually Schwern already has published something like that, but his version is based on randomness. You might call it Symbol::Merge. Or maybe even: Sub::Merge to keep in tradition with Simon Cozens' Sub::Versive. Kay	[reply]
Re: A module to merge packages by Baboon (Acolyte) on Jun 26, 2002 at 13:43 UTC
There is already a module `Sex` which does what you do, and it's available as ActiveState installation package, and also exists on CPAN, version 0.69 Best wishes, I.R.Baboon.	[reply] [d/l]
Re: Re: A module to merge packages by dakkar (Hermit) on Jun 26, 2002 at 13:55 UTC
I know of Schwern's `Sex`, but what the two modules do is different. My `Merge` creates a package whose `@ISA` is a list I specify. `Sex` creates a package by mixing up symbol table entries, both subs and variables, and (by the way) pushing the "parents" into the "child"'s `@ISA`. My first solution was a simplification of `Sex` (with less error checking, no schwernian messages, and no randomness), but it creates problem with classes, and makes it impossible to use `NEXT` to add functionality to a method, in something like: `package a; sub method { my $self=shift; # do something } package b; use NEXT; sub method { my $self=shift; # do something before $self->NEXT::method(@_); # do the normal stuff # do something after } package main; require a;require b; use Merge qw(b a)=>'c'; $c=new c;$c->method; # will call "b"'s implemetation, which will call +"a"'s via NEXT` [download]	[reply] [d/l]