[issue46419] Incomplete Comparison to C++ Methods
New submission from Jorgen Harmse : The description of classes mentions twice that methods are like C++ virtual member functions, but the truth is a bit stranger. Even __init__ seems to act like a virtual function, so there is no guarantee that the base-class part of a derived-class instance is properly constructed. Even if the base class __init__ is called, it may behave erratically. The object is already considered to belong to the derived class, so any method calls will resolve to the derived class. In C++, the run-time type inside any constructor or destructor always matches the compile-time type. Derived-class members are not called because those methods would attempt to use parts of the object that haven't been constructed yet or have already been destructed. Python takes no such precautions, and programmers should be warned accordingly. (I think the solution is to be very careful of calling any other method from __init__.) -- assignee: docs@python components: Documentation messages: 410823 nosy: docs@python, jharmse priority: normal severity: normal status: open title: Incomplete Comparison to C++ Methods type: enhancement versions: Python 3.11 ___ Python tracker <https://bugs.python.org/issue46419> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue46419] Incomplete Comparison to C++ Methods
Jorgen Harmse added the comment: There may be more people who use Python, but there are strange semantics that cause problems even for experienced Python programmers. For example, assign-by-reference (apparently built without considering the solutions available in MatLab & R) frequently leads to unexpected changes in the caller's space. I expect that very few people understand linearisation, so multiple inheritance is effectively unusable in Python. C++ would generate a compile-time error if two base classes provided the same method (unless they inherited it from a common virtual base class). The text in question appears twice in Section 9 of https://docs.python.org/3/tutorial/classes.html. It's in the third paragraph of the introduction and the 5th text paragraph of Section 9.5. -- ___ Python tracker <https://bugs.python.org/issue46419> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue46419] Incomplete Comparison to C++ Methods
Jorgen Harmse added the comment: Is van Rossum serious? I responded to the comments on my report. The action is to clarify the documentation, probably including a warning against multiple inheritance. -- ___ Python tracker <https://bugs.python.org/issue46419> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
