How do I hard-code variables in a dynamically created function in python?

August 13, 2022

I have the following python3 code

class Test:
    pos = [0,0]
    actions = []
    def bar(self, target):
        for i in target:
            def _():
                print(i,end="")
            self.actions.append(_)
foo = Test()
foo.bar("abcd")
for i in foo.actions:
    i()

Which is meant to output:
abcd

but instead it outputs:
dddd

I’m pretty sure the function is using the value of i when executing (the last value i had) and not i’s value the function _ is declared, which is what I want.

>Solution :

The general solution to this is to store the value as a default parameter value, like this:

class Test:
    pos = [0,0]
    actions = []
    def bar(self, target):
        for i in target:
            def _(i=i):  # This is the only changed line
                print(i,end="")
            self.actions.append(_)
foo = Test()
foo.bar("abcd")
for i in foo.actions:
    I()

>>> abcd