On Sun, Oct 28, 2018 at 12:53 PM Joy Diamond <python....@gmail.com> wrote: >> - type(x) and x.__class__ don't necessarily agree; under what >> circumstances are each used? >> >> (I've asked this before, and either never got a good answer, or I can't >> keep it straight in my head.) >> >> - what precisely does type(x) do? > > > 1. `type(x)` gets the true actual type of `x`. > 2. `x.__class__` gets the `.__class__` attribute for `x`, which by default > gets the actual true type of `x`, but may be replace by the user to do other > stuff. >
Not that simple. >>> class X: ... cls = "X" ... >>> class Y: ... cls = "Y" ... >>> x = X() >>> x.__class__ = Y >>> x.cls 'Y' >>> type(x) <class '__main__.Y'> I don't know what the "true actual type" is, since I just changed it. In this case, type() and __class__ do exactly the same thing. The only way I know of (in Py3) to have them show different values is to make __class__ a property, and if you do that, I have no idea what uses the property and what uses type(). Maybe this needs to be actually documented somewhere. It keeps on being a point of confusion. ChrisA _______________________________________________ Python-ideas mailing list Python-ideas@python.org https://mail.python.org/mailman/listinfo/python-ideas Code of Conduct: http://python.org/psf/codeofconduct/
