Fix a SyntaxError on Python 2.6 and early versions of 2.7.
Review Request #10113 — Created Aug. 3, 2018 and submitted
exec()in Python has had two forms over the years:
exec 'code' in globals, locals
exec('code', globals, locals)
The first form was the original, and the second was added early in
Python's life (and is now the only allowed form in 3.x). Unfortunately,
when executing inside a function that contains a subfunction (or when
defining a subfunction in the executed code), some versions of Python
prior to 2.7.9 had an issue factoring in the local variables and would
throw a SyntaxError stating:
SyntaxError: unqualified exec is not allowed in function '__init__' it contains a nested function with free variables
We can avoid this by using
eval(compile(..., 'exec')), which will
provide the results we want in a way that's compatible with all versions
Tested on Python 2.6 through 3.7.