The difference between
This question already has an answer here:
__str__ and __repr__ are both methods for getting a string representation of an object. __str__ is supposed to be shorter and more user-friendly, while __repr__ is supposed to provide more detail.
Specifically, for many data types, __repr__ returns a string that, if you pasted it back into Python, would be a valid expression whose value would be equal to the original value. For instance, str('Hello') returns 'Hello' , but repr('Hello') returns "'Hello'" , with quote marks inside the string. If you printed that string out, you'd get 'Hello' , and if you pasted that back into Python, you'd get the original string back.
Some data types, like file objects, can't be converted to strings this way. The __repr__ methods of such objects usually return a string in angle brackets that includes the object's data type and memory address. User-defined classes also do this if you don't specifically define the __repr__ method.
When you compute a value in the REPL, Python calls __repr__ to convert it into a string. When you use print , however, Python calls __str__ .
When you call print((Item("Car"),)) , you're calling the __str__ method of the tuple class, which is the same as its __repr__ method. That method works by calling the __repr__ method of each item in the tuple, joining them together with commas (plus a trailing one for a one-item tuple), and surrounding the whole thing with parentheses. I'm not sure why the __str__ method of tuple doesn't call __str__ on its contents, but it doesn't.
下一篇: 和...之间的不同