Bug #117159 for Moose: problem with role trait which consumes another role trait

On Tue Aug 23 05:45:43 2016, toby@inf.ed.ac.uk wrote: Show quoted text
I'm not totally sure if I'm following, but it looks like you expect the application of a trait to _also_ export anything provided by that trait. I don't think this was ever an _intentional_ behavior in Moose::Exporter (at least not the parts I wrote). Moose::Exporter is there to let you write modules that act like Moose _when you directly import them_. It's hard for me to imagine how this ever could have worked, but Moose::Exporter is some complex code. I certainly don't think this behavior would be a desired feature, since it seems awfully surprising that simply applying a trait would also import some subs. FWIW, nothing jumps out for me in a diff of Moose::Exporter from 2.1005 to HEAD . Regardless, I suggest you separate the "is a trait" code from the "exports a meta-wrapping sub" code into separate packages: package MyRole; use Moose::Role -traits => 'Foo'; use Foo::ExportsSomething; Cheers, -dave

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Hi Dave, Thanks for your reply. The intention behind the original code is so we can do something like this... Trait1 exports some subs using Moose::Exporter Trait2 consumes Trait1 and also exports (different) subs using Moose::Exporter So, then we could do... use Moose::Role -traits => 'Trait1'; (and use the subs which Trait1 exports) ...or ... use Moose::Role -traits => 'Trait2'; (and use the subs that _both_ Trait1 and Trait2 export) This used to work, but am I right in saying that you think this only ever worked unintentionally? I can try and rework code along the lines you suggest, but I note I can't seem to use more than one trait which use Moose::Exporter... package Test::Meta::Role::Trait::Trait1; use Moose::Role; Moose::Exporter->setup_import_methods( with_meta => [ 'trait1sub' ], also => 'Moose::Role', ); sub trait1sub { my $meta = shift; print "trait1sub\n"; } no Moose::Role; package Moose::Meta::Role::Custom::Trait::Trait1; sub register_implementation {'Test::Meta::Role::Trait::Trait1'}; 1; package Test::Meta::Role::Trait::Trait2; use Moose::Role; Moose::Exporter->setup_import_methods( with_meta => [ 'trait2sub' ], also => 'Moose::Role', ); sub trait2sub { my $meta = shift; print "trait2sub\n"; } no Moose::Role; package Moose::Meta::Role::Custom::Trait::Trait2; sub register_implementation {'Test::Meta::Role::Trait::Trait2'}; 1; package Test::TestRole; use Test::Meta::Role::Trait::Trait1; use Test::Meta::Role::Trait::Trait2; use Moose::Role -traits => [ 'Trait1', 'Trait2' ]; no Moose::Role; 1; On 2.1005: [mambo]toby: perl -Ilib -MTest::TestRole ^C [mambo]toby: On 2.1804: [bolt]toby: perl -Ilib -MTest::TestRole Due to method name conflicts in roles 'Test::Meta::Role::Trait::Trait1' and 'Test::Meta::Role::Trait::Trait2', the methods 'import' and 'unimport' must be implemented or excluded by 'Moose::Meta::Class::__ANON__::SERIAL::1' at /usr/lib64/perl5/vendor_perl/Moose/Exporter.pm line 510 Moose::Role::import('Moose::Role') called at lib/Test/TestRole.pm line 5 Test::TestRole::BEGIN at lib/Test/TestRole.pm line 5 eval {...} at lib/Test/TestRole.pm line 5 require Test/TestRole.pm at - line 0 main::BEGIN at lib/Test/TestRole.pm line 5 eval {...} at lib/Test/TestRole.pm line 5 BEGIN failed--compilation aborted at lib/Test/TestRole.pm line 5. Compilation failed in require. BEGIN failed--compilation aborted. [bolt]toby: Perhaps I'm misunderstanding the intended usage of Moose::Exporter? I didn't write the code in question, just inherited it. Thanks again for your input into this. Cheers Toby -- The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336.

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OK, will do, thanks for clarifying all of this. I've got something which I think kind of works, so will factor it into something that makes sense in the (much more complex) project which requires it. I'm happy for you to close this bug now. Cheers Toby -- The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336.