Upcoming Python features brought to you by Python Enhancement Proposals

Re:Upcoming Python features brought to you by Python Enhance... by eloisius on Monday February 14, 2022 @09:54AM (#30332675)

So it’s not specific to functions as arguments? A long-time gripe I’ve had about default parameters in Python is that they are static from function definition time instead of dynamic at call time. A consequence of that is that if you have a function like

    def foo(bar, baz=[]):
        baz.append(bar)
        return baz

baz will be reused for the duration of the process kind of like a global variable.

If this new syntax fixes that, I see the value.

[ Parent | on HN ]

Re:Upcoming Python features brought to you by Python Enhance... by Sohcahtoa82 on Monday February 14, 2022 @03:51PM (#30338118)

> If this new syntax fixes that, I see the value.

It does. The old syntax creates and assigns the variable at compile-time. => does it at execution time.

So this code:

    def foo(bar, baz=[]):
        baz.append(bar)
        return baz
    foo(1)
    foo(2)
    print(foo(3))

would print '[1, 2, 3]'

But this code:

    def foo(bar, baz=>[]):
        baz.append(bar)
        return baz
    foo(1)
    foo(2)
    print(foo(3))

would print '[3]'

[ Parent | on HN ]