Bug #90805 for Moops: Strange compile errors when consuming Moops roles from Moose

Mon Nov 25 11:58:58 2013 pdcawley [...] bofh.org.uk - Ticket created

Subject:	Strange compile errors when consuming Moops roles from Moose
Date:	Mon, 25 Nov 2013 16:58:44 +0000
To:	bug-Moops [...] rt.cpan.org
From:	Piers Cawley <pdcawley [...] bofh.org.uk>

It turns out that consuming a Moops role from plain old Moose is surprisingly tricky. Suppose I have: use Moops; role Example using Moose { method foo { 'bar' } } then, when I write: perl -E 'package Consumer; use Moose; with 'Example'; package main; say Consumer->new->foo' compilation blows up complaining that I can only consume roles, and Example is not a moose role. However, when I do: perl -MExample -E '...' All is well. As it is when I do: perl -E 'use Example; package Consumer; ...' and even (this one surprised me) perl -E 'require Example; package Consumer; ...' But, if I do: perl -E 'package Consumer; use Example; ...' we're back to blowing up with the same error. I'm seeing this with perl 5.18.1, Moose 2.1005, Moops 0.26, Kavorka 0.019, Keyword::Simple 0.02, Module::Runtime 0.013 if that's of any use. Sorry this bug doesn't come with a .t file, but I couldn't work out how to write one to express the issues correctly.

Mon Nov 25 18:05:48 2013 perl [...] toby.ink - Correspondence added

Hmmm... You may want to add the following to the top of your Example.pm: package main; When Perl loads a module, if it doesn't explicitly start with a package statement, everything within is dumped into the currently compiling package. This means that the "Example" role is actually getting created as "Consumer::Example". I need to mention this in the docs.

Mon Nov 25 18:05:48 2013 The RT System itself - Status changed from 'new' to 'open'

Tue Nov 26 05:00:33 2013 pdcawley [...] bofh.org.uk - Correspondence added

Subject:	Re: [rt.cpan.org #90805] Strange compile errors when consuming Moops roles from Moose
Date:	Tue, 26 Nov 2013 10:00:15 +0000
To:	bug-Moops [...] rt.cpan.org
From:	Piers Cawley <pdcawley [...] bofh.org.uk>

Eek! That's kind of icky. Is there any way of making 'use Moops' force the package back to 'main'. Some sort of: use Moops -toplevel which one could use to tell Moops not to nest the package? Or (probably better) use lexical hints to manage auto nesting of Moops packages rather than dynamic scope because the current behaviour seems utterly... well, at the very least, surprising. On 25 November 2013 23:05, Toby Inkster via RT <bug-Moops@rt.cpan.org>wrote: Show quoted text

> <URL: https://rt.cpan.org/Ticket/Display.html?id=90805 > > > Hmmm... You may want to add the following to the top of your Example.pm: > > package main; > > When Perl loads a module, if it doesn't explicitly start with a package > statement, everything within is dumped into the currently compiling > package. This means that the "Example" role is actually getting created as > "Consumer::Example". > > I need to mention this in the docs. >

Tue Nov 26 17:31:35 2013 perl [...] toby.ink - Correspondence added

Unless there's a good reason not to, I'm trying to act similar to p5-mop, which in this case does the same thing. There have been a few people in the #p5-mop IRC channel similarly confused, so things may change in p5-mop, in which case Moops will probably change to match. Note that this issue only effects packages which contain no "::" in their names. You can add a leading "::" to work around it: use Moops; role ::Example using Moose { method foo { 'bar' } }

Sat Aug 16 17:10:59 2014 perl [...] toby.ink - Correspondence added

Moops now includes a test case along these lines... https://metacpan.org/source/TOBYINK/Moops-0.033/t/04composition.t Roles are now composed with the class at the *end* of the class declaration. So this: class Foo with Bar { method xyz { ... } } is roughly equivalent to: package Foo { use Moo; *xyz = sub { ... }; with "Bar"; } Sometimes, like if in your class you want to apply method modifiers to methods that were defined in your role, this order screws things up, but at least it's simple and understandable, and has an easy fix. The fix being to use `with` *inside* the class declaration instead of at the top.

Sat Aug 16 17:11:15 2014 perl [...] toby.ink - Status changed from 'open' to 'resolved'