implement __hash__ in a way that preserves C++ object identity #29

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john · 2024-03-09T19:01:55Z

john commented

2024-03-09 19:01:55 +00:00

Notes say:
34 feat: All python objects that wrap C++ classes should return the "data" pointer address as a hash, so that "is" operator will work on UI objects or collections generated as different Python objects

PyUIDrawable derived class implementations pretty universally use data as a std::shared_ptr<UIDerivedSomethingOrOther>. The actual pointer address inside that shared pointer is the object, and it's how live changes are made.
But the PyTYPE_HEAD or whatever holds the Python object info can be duplicated - multiple Python objects can hold shared pointers to the same C++ object. Totally intentional.
If Python objects point to the same C++ object, a is b should return True.

Notes say: 34 feat: All python objects that wrap C++ classes should return the "data" pointer address as a hash, so that "is" operator will work on UI objects or collections generated as different Python objects * PyUIDrawable derived class implementations pretty universally use `data` as a `std::shared_ptr<UIDerivedSomethingOrOther>`. The actual pointer address inside that shared pointer *is* the object, and it's how live changes are made. * But the `PyTYPE_HEAD` or whatever holds the Python object info can be duplicated - multiple Python objects can hold shared pointers to the same C++ object. Totally intentional. * If Python objects point to the same C++ object, `a is b` should return `True`.

john added the

Tiny Feature

label 2024-03-09 19:02:10 +00:00

john referenced this issue

2024-03-09 19:07:19 +00:00

UIGrid & UIEntity Integration; reliable add and remove #30

john added this to the Fun, Convenient McRogueFace Objects project 2024-03-13 14:49:53 +00:00

john commented

2024-04-20 18:23:16 +00:00

wontfix / the current usage of hash is probably incorrect and should be deprecated. Hashable object should be immutable. So the mcrf data containers probably should not have this value.

john closed this issue

2024-04-20 18:23:16 +00:00

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