(Python) I have a string that represents an existing global variable's name, and would like to pass this to a function

Question

x=1

def hi(y):
    exec("global " + y) 
    exec(y + "+=1")

hi("x")
print(x)

I'd like the globally defined x to be incremented by 1, but the output I get is still 1. How can I correct this?

This looks very much like a XY problem http://meta.stackexchange.com/questions/66377/what-is-the-xy-problem — Irmen de Jong, Feb 24 '17 at 20:52

score 2 · Accepted Answer · answered Feb 24 '17 at 20:41

2

You can access globals by a special keyword, wait for it: globals :)

def hi(var):
    globals()[var] += 1

answered Feb 24 '17 at 20:41

bosnjak

score 1 · Answer 2 · edited May 23 '17 at 12:31

Avoid exec like the plague (till you know what problems it introduces or in 5 years, which ever is later)
single letter variable names is a no-no for future readability sake. (it might just be for a demo but I'm saying...)
check out this link for scoping rules (with good examples for globals in further posts)

Hope the person passing in 'x' doesn't change it to a invalid variable name like hi(12345).

2 Answers2