A function receives a reference to (and will access) the same object in memory as used by the caller.
However, it does not receive the box that the caller is storing this object in; as in pass-by-value,
the function provides its own box and creates a new variable for itself.
| Box | Object | |
| Pass-By-Reference | Same box | Same Object |
| Pass-By-Value | Different box | Different value |
| Pass-By-Object | Different box | Same object |
dis.dis() prints the byte-code instruction.
list += [1,2] : INPLACE_ADD
list = list + [1,2] : BINARY_ADD
Python gives types a way to handle += specially, by creating an __iadd__ method as well as an __add__.
The intention is that mutable types, like list, will mutate themselves in __iadd__ (and then return self, unless you‘re doing something very tricky)
Referenced by:
1. https://stackoverflow.com/questions/15376509/when-is-i-x-different-from-i-i-x-in-python
2. https://robertheaton.com/2014/02/09/pythons-pass-by-object-reference-as-explained-by-philip-k-dick/
Python pass-by-object-reference [TBC]
原文：https://www.cnblogs.com/noralee/p/12173462.html