问题
I read many article about how to implement multimethod in c++:
- http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2003/n1529.html
- http://www.codeproject.com/KB/recipes/mmcppfcs.aspx
- http://lambda-the-ultimate.org/node/2590
- http://parasol.tamu.edu/people/peterp/omm/
why there are no multimethod in c++?
why do not they get supported by c++ standard?
回答1:
Straight from the horse's mouth:
"I rejected multi-methods with regret, because I liked the idea, but couldn't find an acceptable form under which to accept it."
Bjarne Stroustrup, The Design and Evolution of C++ (p297)
And later:
"Multi-methods is one of the interesting what-ifs of C++. Could I have designed and implemented them well enough at the time? [...] What other work might have been left undone to provide the time to design and implement multi-methods?"
(p298f)
In general, whenever you feel the urge to know why some particular C++ feature was implemented, or was not implemented, or was implemented the way it is now, and if that feature pre-dates the standardization, you want to read D&E.
回答2:
As Bjarne has pointed out a number of times, when people criticize C++, it usually runs something like: "C++ is too big, too complex, has too many features, and it's too hard to learn -- you should really work at making it smaller and simpler. Oh, and while you're working on that I also have this really great idea for a killer feature that you should add!"
回答3:
Just because it could be done doesn't mean it's a problem that it wasn't done. One criticism of C++ is along the lines of "Stroustrup took everything anyone had heard of, and tried to include it."
Plus, as Raymond Chen says, "Every feature starts off with -100 points." That is, before you ask why C++ doesn't have these things, you should explain in detail why it needs them. Otherwise your feature stays in negative territory, due to the costs associated with it.
来源：https://stackoverflow.com/questions/4844669/why-there-are-no-multimethods-in-c