On Sat, May 2, 2020 at 10:17 AM Terry Reedy <tjre...@udel.edu> wrote: > > On 5/1/2020 7:30 PM, Chris Angelico wrote: > > > @static(called=0) > > def other_function(): > > me.called += 1 > > ... > > > > Obviously the name "me" can't be used, as it'd break a bunch of code, > > but conceptually this would be incredibly helpful. It'd also be a > > reliable idiom for recursion optimization - any "me()" is guaranteed > > to be recursion and may potentially give info to an optimizer. > > > > Perhaps, if Python had a way to identify the current function, it > > would feel less odd to attach attributes to it. > > As one might imagine, something so 'obvious' has been proposed multiple > times. Reasons for repeated rejection. > > 1. Function bodies are compiled to code objects. There is no function > to 'bind' to and there might never be. (compile(code_body, ...)).
True, but that's a bit of an edge case. I'm sure there are other edge cases too - what happens with a 'nonlocal' if it's in a code object outside of a function? (Or in the CPython implementation, what happens with the corresponding cell lookup?) If <me> causes a RuntimeError if used in such a context, or if the compilation of <me> creates some sort of reference that simply doesn't work outside of a function, it'd be fine. > 2. Python does name resolution on function bodies when called. If early > binding of <me> were possible, it would be an exception. It would have to be a keyword of a sort. Not necessarily an actual keyword, although that would definitely work. > 3. Recursion without names is really hard; hence the special > head-spinning combinator to do that. And that's a good reason to have compiler support for it. It would make true recursion simple. (Obviously mutual recursion would still require names.) > 4. The post-compile function object address would only be useful for > CPYthon, not for implementations that move objects around. Why? It's an object. It should be possible to reference it. > 5. The automatic conversion of recursion to a while loop only works for > linear tail recursion. In Python, such cases are usually better written > directly as a for-loop. True, and that would probably only be a small advantage anyway. But it's also a clarity thing, and it means you don't have to name your function inside the function and then remember to rename it. There is another objection though: 6. Decorated functions would behave differently based on whether you call by name or call by <me>. I don't have an answer to that, other than that giving programmers the option isn't a bad thing. People would just have to be aware of the distinction and know which one they want. ChrisA _______________________________________________ Python-ideas mailing list -- python-ideas@python.org To unsubscribe send an email to python-ideas-le...@python.org https://mail.python.org/mailman3/lists/python-ideas.python.org/ Message archived at https://mail.python.org/archives/list/python-ideas@python.org/message/ILIKVTXX5B7P3HNVUJES27DYM3WBE3GC/ Code of Conduct: http://python.org/psf/codeofconduct/
