Brian Allen Vanderburg II a écrit :
bock...@virgilio.it wrote:
Constants would be a nice addition in python, sure enough.
But I'm not sure that this can be done without a run-time check every
time
the constant is used, and python is already slow enough. Maybe a check
that is disabled when running with optimizing flags ?
But I'm sure this discussion has been already made and the FINAL WORD has
been already spoken.
One idea to make constants possible would be to extend properties to be
able to exist at the module level as well as the class level:
@property
def pi():
return 3.14159.....
print(pi) # prints 3.14159....
pi=32 # Raise an error Cannot set attribute ...
There are a couple problems with this suggestion:
- it would require modifying lookup rules to allow the protocol
descriptor to be invoked on instance attributes[1] - which is not
actually the case, by design.
- it adds the overhead of a method and a function call for what is
mostly a simple "constant" attribute lookup.
FWIW, while it would already work for class-level pseudo-constants
(using a very simple custom descriptor), I'd qualify such usage as a WTF.
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