Questions about `locals` builtin

[Steven D'Aprano]

On Wed, 28 Feb 2018 18:01:42 +1100, Chris Angelico wrote:

> If you really want a list of ALL the local names in a function, you can
> look at its __code__ object, which has a tuple of variable names:
> 
> print(func1.__code__.co_varnames)
> 
> That information is static to the function, as it is indeed determined
> when the function is compiled.

Ho ho ho, not in Python 2 it isn't!!!

py> def bizarre():
...     x = 1
...     from math import *  # oww my aching head!
...     print 'sin' in locals()
...     print sin
...
<stdin>:1: SyntaxWarning: import * only allowed at module level
py> bizarre()
True
<built-in function sin>
py> bizarre.__code__.co_varnames
('x',)


In Python 2, you can also use exec inside a function, for extra 
obfuscatory goodness.

Python 3 locks down these loopholes, and ensures that locals inside 
functions can be statically determined.



-- 
Steve