Ian Kelly wrote:
On Wed, Feb 1, 2012 at 3:24 PM, Ethan Furman <et...@stoneleaf.us> wrote:
Definitely should rely on it, because in CPython 3 exec does not un-optimize
the function and assigning to locals() will not actually change the
functions variables.
Well, the former is not surprising, since exec was changed from a
statement to a built-in. I don't see any difference in the way
locals() behaves, though:
Python 3.2 (r32:88445, Feb 20 2011, 21:29:02) [MSC v.1500 32 bit (Intel)] on win
32
Type "help", "copyright", "credits" or "license" for more information.
def f(x, y):
... locals()[x] = y
... print(vars())
... exec('print(' + x + ')')
...
f('a', 42)
{'y': 42, 'x': 'a', 'a': 42}
42
That still seems to work as I described it. You couldn't directly
reference it as 'a', though, since the result would be either that it
would try to look up a global with that name, or the compiler would
consider it a local, optimize it, and then you could no longer assign
it via locals().
Cheers,
Ian
--> def f(x, y):
... locals()[x] = y
... print(vars())
... exec('print (' + x + ')')
... print(x)
...
--> f('a', 42)
{'y': 42, 'x': 'a', 'a': 42}
42
a
Indeed -- the point to keep in mind is that locals() can become out of
sync with the functions actual variables. Definitely falls in the camp
of "if you don't know *exactly* what you are doing, do not play this way!"
~Ethan~
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