Structured bindings in Python

user_14277568 0
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C++17 introduced the new structured bindings syntax:

std::pair<int, int> p = {1, 2};
auto [a, b] = p;

Is there something similar in python3? I was thinking of using the "splat" operator to bind class variables to a list, which can be unpacked and assigned to multiple variables like such:

class pair:
    def __init__(self, first, second):
        self.first = first
        self.second = second
...

p = pair(1, 2)
a, b = *p

Is this possible? And if so, how would I go by implementing this to work for my own classes?

A tuple in Python works as a simple solution to this problem. However, built in types don't give much flexibility in implementing other class methods.

python c++
3 Answers

Yes, you can use __iter__ method since iterators can be unpacked too:

class pair:
    def __init__(self, first, second):
        self.first = first
        self.second = second
    def __iter__(self):
        # Use tuple's iterator since it is the closest to our use case.
        return iter((self.first, self.second))
user_76917290

You can use tuples and tuple unpacking (see the bottom of this section in the Python documentation):

p = (1, 2)
a, b = p
print(a, b) # Prints 1 2
user_177698150

An alternative with dataclass:

from dataclasses import dataclass, astuple

@dataclass
class pair:
    first: int
    second: int

p = pair(1, 2)
a, b = astuple(p)
print(a, b)

Output (Try it online!):

1 2
user_126710570
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