How to convert an custom class object to a tuple in Python? [closed]

Question

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) 

We will be able to define how to convert the object to the str class (into a string):

    a = Point(1, 1)     b = str(a)     print(b) 

I know that we can define the string representation of a custom-defined object, but how do we define the list —more precisely, tuple— representation of an object?

Answer 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.