The implementation mechanism of variable exchange x,y=y,x--tuple

There is an assignment mechanism in Python that assigns values in this way, and the objects on both sides of the equal sign are tuples and the parentheses of the tuples are optional. The usual form is

' A String '

Equal to (x, y, Z) = (1, 2, 'a string')

The most frequently used environment for this type of assignment is variable exchange, which is shaped like

X, y = y, X

This exchange method does not require an intermediate variable to exchange the values of two variables. So what is the concrete implementation mechanism?

At run time, first constructs a tuple (y, x), then constructs another tuple (x, y), then assigns (x, y) with tuples (y, x), and the tuple assignment process is left to right and sequentially. If x=1,y=2, shilling x=y, at this time x=2, then make y=x,y should be equal to 2? So the variable exchange is not possible? For this problem, you should start with the characteristics of the tuple.

' A String '  = (x, y, z)

Variable names x, Y, Z are references, memory opens up except three spaces that store 1, 2, ' A string ', three variables pointing to the three-block address respectively. The tuple, constructed of these three variables, has three elements, three of which are not the three variables of x, Y, Z, but the contents of the address space to which the three variables point. If at this point another x=4, at this time in the address space will open up another space storage 4,x and then point to this space, and the tuple of three values remain unchanged.

So for x, y = y, x , the tuple (y,x), first composed by y,x, should be represented as (2,1), then the value of the variable can be exchanged from left to right.

The implementation mechanism of variable exchange x,y=y,x--tuple