On 27 September 2016 at 17:29, Neil Girdhar <mistersh...@gmail.com> wrote: > On Friday, September 23, 2016 at 2:23:58 AM UTC-4, Nick Coghlan wrote: >> The difference between that and the "methods referring to the class >> they're defined in" case is that it's likely to be pretty normal to >> want to do the latter, so it may prove worthwhile to provide a cleaner >> standard spelling for it. The counter-argument is the general >> circularity one above: do you *really* need instances of the >> particular class being defined? Or is there a more permissive >> interface based type signature you could specify instead? Or perhaps >> no type signature at all, and let ducktyping sort it out implicitly at >> runtime? > > I agree that circularity should in general be avoided, but it's not always > possible or elegant to do that. Sometimes you really need two classes to > refer to each other. In that case, why not expose your placeholder idea to > the user via a library? You have one function that generates placeholder > singletons (generate_placeholder()), and another function to walks a class > object and replaces a placeholder with a given value > (replace_placeholder(placeholder, cls, value)).
Because the general case is already covered by using a quoted string instead of a name reference. "I don't like using strings to denote delayed evaluation" isn't a compelling argument, which is why alternative ideas have to offer some other significant benefit, or else be incredibly simple both to implement and to explain. Cheers, Nick. -- Nick Coghlan | ncogh...@gmail.com | Brisbane, Australia _______________________________________________ Python-ideas mailing list Python-ideas@python.org https://mail.python.org/mailman/listinfo/python-ideas Code of Conduct: http://python.org/psf/codeofconduct/
