"Burn in" a global variable on function definition

Asked Apr 27 '17 at 01:37

Active Apr 27 '17 at 02:04

Viewed 191 times

What is the way to "burn in" an external variable to a function upon definition?

funcs = []
for n in range(5):
    def f(x):
        return n * x
    funcs.append(f)

del n

But trying

[g(2) for g in funcs]

funcs[1](2)

Gives an error

NameError: name 'n' is not defined

Is there a way to allow defining a function with a parameter which will become fixed for the function scope?

edited Apr 27 '17 at 01:54

asked Apr 27 '17 at 01:37

Aguy

2

Your code works fine as written, although, you are probably not generating the functions you think you are due to the lexical scoping of python closures (n will be the value `n` had in the scope the functions were defined, i.e. `n == 4` for all the functions in `funcs` – juanpa.arrivillaga Apr 27 '17 at 01:43
Wait, did you explicitely `del n`??? That isn't what was there originally... – juanpa.arrivillaga Apr 27 '17 at 01:45
Try this `g=lambda x:[n*x for n in range(5)]` `g(2)` – McGrady Apr 27 '17 at 01:46
2

@McGrady why? The code works fine as written... except for the `del n` which was added by an edit... – juanpa.arrivillaga Apr 27 '17 at 01:46

0 Answers0