Re: Role1 with attribute matches requires on Role2
[email protected] (Ovid)
| Newsgroups | perl.moose |
|---|---|
| Message-ID | <[email protected]> |
From: Jesse Luehrs <[email protected]> >To: Pedro Melo <[email protected]> >Cc: moose <[email protected]> >Sent: Friday, 1 March 2013, 18:05 >Subject: Re: Role1 with attribute matches requires on Role2 > >On Fri, Mar 01, 2013 at 04:56:57PM +0000, Pedro Melo wrote: >> Hi, >> >> I keep getting bitten by this, and I was wondering if this is >> something that will be solved eventually, or its something that would >> be nice to solve but it is actually tricky to do, or just that I'm >> doing it wrong. >> >> I have two roles, R1 and R2. R1 defines a attribute ctx. R2 requires a 'ctx'. >> >> If I use the two roles on a class C, with a single "with 'R1', 'R2';" I get >> >> 'R1|R2' requires the method 'ctx' to be implemented by 'C' >> >> I can work around it with two "with 'R1'; with 'R2';". But I loose all >> the other protections wrt duplicate methods I might have in R1 and R2. >> >> Opinions? > >This is something that we'd like to fix - the problem is mainly that >role accessors aren't generated until they are composed into a class, >but role application composes roles together before composing them into >the class. What we really need to do is provide a way for roles to say >"I'm going to generate a method of this name", which we would be able to >query during the role summation process (we can't actually generate the >methods themselves because doing so requires an instance metaclass, >which only classes have). > >Patches to fix this would be appreciated. Out of curiosity, how is this handled in the internals? Does the role composition do a simple ->can() check for methods? If so, during composition, could has() fake a forward declaration? { package Foo; sub bar; } say "yes" if Foo->can('bar'); You're not actually creating the method yet, but you're promising that it will be there. Cheers, Ovid -- Twitter - http://twitter.com/OvidPerl/ Buy my book - http://bit.ly/beginning_perl Buy my other book - http://www.oreilly.com/catalog/perlhks/ Live and work overseas - http://www.overseas-exile.com/