Georg Brandl added the comment: The patch is definitely an improvement. What about a remark like ", except that `deco` is evaluated before the function `f` is created"? That should cover the remaining difference. ---------- nosy: +georg.brandl _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue26576> _______________________________________

Chris Angelico added the comment: The remaining difference that's actually of use, perhaps. But the decoration itself happens before the name is bound. It's impossible to describe in Python code; but it can be probed - you can monkeypatch a class using a decorator: def monkeypatch(cls): orig = globals()[cls.__name__] # Undocumented magic print("Monkeypatch",id(cls),"into",id(orig)) for attr in dir(cls): if not attr.startswith("_"): setattr(orig,attr,getattr(cls,attr)) return orig class Foo: def method1(self): print("I am method 1") print("Foo is currently",id(Foo)) some_object = Foo() @monkeypatch class Foo: def method2(self): print("I am method 2") print("Foo is now",id(Foo)) some_object.method1() some_object.method2() Is this undocumented behaviour? Should it be supported? It works on every Python I've tried it on (CPython 2.7 and 3.6, PyPy2 and PyPy3, Jython, and MicroPython), but it's not something I'd depend on in production code unless it's documented. ---------- _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue26576> _______________________________________

Georg Brandl added the comment: That is definitely supported. Whether it's actually useful to document, I'm not sure. "except that the original function is not temporarily bound to the name `f`" could work. ---------- _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue26576> _______________________________________

Terry J. Reedy added the comment: Guido, the discrepancy between the decorator doc's 'equivalent code' and actual, optimized, behavior with regard to skipping an intermediate binding of the function to the name came up soon after decorators were added. I cannot find the issue, but as I remember, you said at the time that the doc's 'equivalent' code was good enough, and perhaps that you did not want to force the optimization on other implementations (not sure of this latter). This issue has come up often enough on Python list and SO that many think that the actual behavior should be documented. But should it be documented as a guaranteed language feature or as just an optional optimization? ---------- nosy: +gvanrossum, terry.reedy _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue26576> _______________________________________

Chris Angelico added the comment: Sure - changing it to "roughly". I started with that wording, and then changed to "broadly", for reasons which I now can't remember - so they can't have been too important. Consistency wins. ---------- Added file: http://bugs.python.org/file42214/deco-docos.patch _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue26576> _______________________________________

Berker Peksag added the comment: Thanks for the patch, Chris. I've only changed `func` to ``func`` (we don't use single backtick in reST.) ---------- nosy: +berker.peksag resolution: -> fixed stage: -> resolved status: open -> closed type: -> enhancement versions: +Python 3.5, Python 3.6 _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue26576> _______________________________________