On 01/13/2012 10:54 AM, Neil Cerutti wrote:
If you've ever implemented operator=, operator+, and operator+=
in C++ you'll know how and why they are different.
At the same time, you'd also know that that implementing them in such a
way that 'a += b' does *not* perform the same action as 'a = a + b' is
considered very bad-mannered.
In fact, it's often suggested (e.g. in "More Effective C++"'s Item 22,
though this is not the main thrust of that section) to implement
operator+ in terms of += to ensure that this is the case:
MyType operator+ (MyType left, MyType right) {
MyType copy = left; copy += right; return copy;
}
A C++
programmer would be wondering how either can work on immutable
objects, and that's where Python's magical rebinding semantics
come into play.
IMO a C++ programmer wouldn't be likely to wonder that much at all
because he or she wouldn't view the objects as immutable to begin with.
:-) 'x = 5; x += 1;' makes perfect sense in C++, just for a somewhat
different reason.
Evan
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