Message 197849 - Python tracker (original) (raw)

Tim Peters added the comment:

 ..., _fast=slow, ...

in an argument list means we endure the slow lookup (of slow) only once, when the function is first defined. When the function is called, that binding is available via the local (much faster lookup) variable _fast.

Purely a speed trick, but can make a real difference in very heavily used functions.

Thanks for the answer, Tim. Interesting optimization.