[Python-Dev] PEP 318: Singleton decorator (original) (raw)

Phillip J. Eby pje at telecommunity.com
Tue Mar 30 09:58:06 EST 2004

At 05:17 AM 3/30/04 -0600, Ka-Ping Yee wrote:

Hi folks.

Earlier messages suggested a nice singleton decorator, which is shown in the draft PEP: def singleton(cls): return cls() class MyClass [singleton]: ... This has been mentioned as an argument against requiring or recommending that decorators accept and return callables. But i don't think this is a good way to write a singleton, because then the user of the class has to get instances by saying "MyClass" instead of "MyClass()".

That's a stylistic decision. IMO, it's more pythonic to not call a constructor. One does not, after all, call modules in order to "construct" them, and modules are a prime example of singletons in Python.

What benefit is there to forcing people to perform a call operation that doesn't do anything?

I respectfully suggest that the PEP use the latter implementation in its singleton example instead.

I respectfully disagree. :)

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