问题
If we define __str__ method in a class:
class Point():
def __init__(self, x, y):
self.x = x
self.y = y
def __str__(self, key):
return '{},{}'.format(self.x, self.y)
So we can convert its object to str immediately:
a = Point(1, 1)
b = str(a)
print(b)
But as far as I know, there is not such __tuple__ magic method, so I do not know how to define a class which can pass to tuple() so that we can convert its object to tuple immediately.
回答1:
The tuple "function" (it's really a type, but that means you can call it like a function) will take any iterable, including an iterator, as its argument. So if you want to convert your object to a tuple, just make sure it's iterable. This means implementing an __iter__ method, which should be a generator function (one whose body contains one or more yield expressions). e.g.
>>> class SquaresTo:
... def __init__(self, n):
... self.n = n
... def __iter__(self):
... for i in range(self.n):
... yield i * i
...
>>> s = SquaresTo(5)
>>> tuple(s)
(0, 1, 4, 9, 16)
>>> list(s)
[0, 1, 4, 9, 16]
>>> sum(s)
30
You can see from the example that several Python functions/types will take an iterable as their argument and use the sequence of values that it generates in producing a result.
来源：https://stackoverflow.com/questions/37639363/how-to-convert-an-custom-class-object-to-a-tuple-in-python