[Python-Dev] PyPy, Jython, & IronPython: Enum convenience function and pickleablity (original) (raw)

Antoine Pitrou solipsis at pitrou.net
Thu May 2 22:42:53 CEST 2013

On Thu, 2 May 2013 13:33:21 -0700 Eli Bendersky <eliben at gmail.com> wrote:

On Thu, May 2, 2013 at 1:22 PM, Antoine Pitrou <solipsis at pitrou.net> wrote:

> On Thu, 2 May 2013 13:15:00 -0700 > Eli Bendersky <eliben at gmail.com> wrote: > > > Two things that were suggested in private: > > > > > > 1) ask users to pass the module name to the convenience function > > > explicitly (i.e. pass "seasonmodule.Season" instead of "Season" as the > > > class "name"). Guido doesn't like it :-) > > > > > > 2) dicth the "convenience function" and replace it with a regular > > > class-based syntax. Ethan doesn't like it :-) > > > > > > > Re (2), we already have the hack in stdlib in namedtuple, so not allowing > > it for an enum is a step backwards. > > That's a fallacy. There is no step backwards if you adopt a class-based > syntax, which is just as convenient as the proposed "convenience > function". I have a hard time understanding that calling a function to > declare a class is suddenly considered "convenient". > > > If > > sys.getframe(1).fglobals['name'] feels hackish, maybe it can be > > shortened to a convenience function the stdlib provides? > > It's not the notation which is hackish, it's the fact that you are > inspecting the frame stack in the hope of getting the right information. > > What if someone wants to write another convenience function that wraps > your convenience function? What if your code is executing from some > kind of step-by-step debugger which inserts an additional frame in the > call stack? What if someone wants the enum to be nested inside another > class (rather than reside at the module top-level)? > Would nesting the non-convenience Enum in a function or a class allow one to pickle it?

Once PEP 3154 is implemented (Alexandre is on it :-)), nested classes should be picklable. As for classes inside functions, it sounds quite impossible (how do you instantiate the function namespace without calling the function?).

Regards

Antoine.

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