[Python-Dev] Impact of Namedtuple on startup time (original) (raw)

Isaac Morland isaac.morland at gmail.com
Mon Jul 17 16:48:02 EDT 2017

My apologies, I misunderstood what had been proposed (and rejected).

So it sounds like the _source is a pre-requisite for the current exec-based implementation, but the proposal is to replace with a non-exec-based implementation, meaning _source would no longer be needed for the module to work and might be eliminated. But _source could continue to be generated lazily (and cached if thought helpful) using an @property, so even the (apparently rare) uses of _source would continue to work.

This would in some sense be a DRY violation, but of a very pragmatic Pythonic sort, where we have two implementations, one for documentation and one for efficiency. How different would this be from all those modules that have both Python and C implementations?

On 17 July 2017 at 09:31, Antoine Pitrou <antoine at python.org> wrote:

Le 17/07/2017 à 15:26, Isaac Morland a écrit : > > I think I understand well enough to say something intelligent… > > While actual references to source are likely rare (certainly I’ve never > used it), my understanding is that the way namedtuple works is to > construct source, and then exec it to create the class. Once that is > done, there is no significant saving to be had by throwing away the > constructed source value. The proposed resolution on https://bugs.python.org/issue28638 is to avoid exec() on most parts of the namedtuple class, hence speeding up the class creation. > I come from > a non-Pythonic background so use of exec still feels a bit weird to me > but I absolutely love namedtuple and use it constantly. I think for most Python programmers, it still feels a bit un-Pythonic. While exec() is part of Python, it's generally only used in fringe cases where nothing else works. Regards Antoine.

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