Antoine Pitrou <pit...@free.fr> added the comment: > Implicit knowledge in your own head about what might or might not be a > good idea to program is not the same thing as a specification. > "type(x) is str" is a good specification in this context, while > "string subclasses, but only if they're really str" does not. > > And the reason why that is, is because the first specification allows > server implementers to say, "your type is not str, so you are not > conformant; go fix your code." The second "specification" is just an > invitation to (number of server implementations)*(number of string > implementations) arguments about what conformance is.
You might argue about this all the way you want, but let me repeat it: the interpreter already, implicitly, uses the "second specification" in many of its internal routines (e.g. C implementations of stdlib functions and types). Why do you think what is fine for the interpreter and its stdlib is not fine for WSGI? > Practicality beats purity, and explicit is better than implicit. And, ironically, you are arguing for a pure specification at the expense of practicality. As for explicit/implicit, it isn't involved here: an isinstance() test is as explicit as a type() equality test. ---------- _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue10935> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
