Luis M. González a écrit :
On Feb 24, 8:48 am, Bruno Desthuilliers <bruno.
42.desthuilli...@websiteburo.invalid> wrote:
Luis M. Gonz lez a crit :
And what about the trick of updating globals? Is it legal?
It's legal, but it's (usually) a very bad idea - at the top-level, it
harms readability, and from within a function it's doubly bad
(readibility + "globals are evil").
Now as usual with GoldenRules(tm), it's meant to be broken - once you do
know why you shouldn't _usually_ do it.
If not, is
there any "legal" way to do what the OP needs?
I still don't understand why is it a bad idea in the case of
globals().
please not the _usually_.
This is the only way I know to define variables programatically in the
top-level namespace, without having to do it manually one by one.
I don't see the readability problem either.
# wrong.py
x = 42
def bar():
return x + 1
def test():
y = bar()
assert y==43
# snip 1kloc
def foo():
globals()[x] = 43
quux()
# snip some more core
def quux():
globals()[y] = 1138
# snip some more core
if __name__ == '__main__':
foo()
Enjoy...
Talking about Goldenrules(tm), what's the recomended way to do it?
The "recommanded way" is
1/ to avoid using globals to share state whenever possible
2/ to avoid creating globals from a function
If your problem is to conditionnaly define globals (based on environment
value or whatnot), then just write the conditional at the top level.
Now I don't say there's no legitimate use case for updating the global
namespace from within a function - just that this is a very very very
rare beast (never meet her as far as I'm concerned, and I did write some
hairy code), and even then is BadEnough(tm) to require a good documentation.
FWIW, your example seemed to be about updating the global namespace from
within a function just to have the names available in the function,
which is about the worst possible solution to the OP problem.
wrt/ the OP question, mapping a sequence of values to a sequence of
names is a legitimate concern, but you just dont need to define these
names in the local namespace to use them - just stick'em in a dict and
you're fine.
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