1. Object Representations
Every object-oriented language has at least one standard way of getting a string representation from any object. Python has two: repr() and str() . And the special methods __repr__ and __str__ support repr() and str().
There are two additional special methods to support alternative representations of objects: __bytes__ and __format__ . The __bytes__ is called by bytes() to get the object represented as a byte sequence . Regarding __format__ , both the built-in function format() and the str.format() method call it to get string displays of objects using special formatting codes.
# In Python3 , __repr__ , __str__ , and __format__ must always return Unicode strings (type str). Only __bytes__ is supposed to return a byte sequence (type bytes)
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原文：https://www.cnblogs.com/neozheng/p/12289638.html