Re: RFC: Trait expects interface

On Tue, Jan 4, 2022, at 4:35 PM, Kirill Nesmeyanov wrote: > Hello internals! > > Since «traits» are often an indicator of not very good code and many > may not use them quite correctly, for example, as helpers, I suggest > adding support for the expects keyword to indicate that the > trait is > part of the code decomposition taking into account ISP. > > For example: > ``` > // Definition > > trait LoggerTrait expects LoggerInterface > { >     // ... > } > > // Usage > > class MyService > { >     use LoggerTrait; // Fatal Error: Class MyService > expects LoggerInterface to be implemented > } > > class MyService2 implements LoggerInterface > { >     use LoggerTrait; // OK > } > ``` > > How relevant do you think this idea/proposal is? And what possible > problems or solutions will this entail in the future? I can't say this has ever been an issue for me when using traits. I've never had a trait that needed to be used by a class with a given interface. What I usually have is a trait that is a full or mostly implementation of an interface. So this would be much more useful to me: trait LoggerTrait implements LoggerInterface { ... } (Perhaps some way to indicate that it mostly implements, and the rest are abstract methods? Or require the other methods to be explicitly abstract?) I think it's subtly different, as it approaches the question from the other direction. --Larry Garfield