I am trying to declare and change a global variable in an exec string, like this:
ostr = "didn't work"
nstr = "worked"
def function():
exec("global ostr; ostr = nstr")
#global ostr; ostr = nstr
print(ostr)
lv='ostr' in globals()
print(lv)
ostr='asd'
function()
However, this errors out on the print statement with:
UnboundLocalError: local variable 'ostr' referenced before assignment
But, if I comment out the "exec" line and uncomment line after the exec statement, the code works fine.
How can I fix this error using "exec"? I want to declare variables global and modify those global variables inside an exec string and have those modifications visible in "function" on subsequent lines.
You have to declare that you are using global ostr in the function to be able to print it. This piece of code outputs
def function():
global ostr
exec("global ostr; ostr = nstr")
#global ostr; ostr = nstr
print(ostr)
lv='ostr' in globals()
print(lv)
ostr='asd'
worked
True
Edit: Just realised the exec actually works with global variables, if you re-run your code and print(ostr) in the global main you will see it was changed.
ostr = "didn't work"
nstr = "worked"
def function():
#global ostr
exec("global ostr; ostr = nstr")
function()
print(ostr)
worked
Edit#2: Either declare ostr as a global variable before modifying it, or assign it to another local variable.
ostr = "didn't work"
nstr = "worked"
def function():
exec("global ostr; ostr = nstr")
#global ostr; ostr = nstr
print(ostr)
lv='ostr' in globals()
print(lv)
function()
worked
True
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