I’m sporadically working on what could roughly be called “reducing techincal debt” on a Python project that’s been around for a long time (20 years), and ran into what was an oddity to me… some utility functions that use default arguments that are the same as builtins. That sounds a little odd, so for illustration (this particular paste is fictitious, but real function signatures do contain these two and more):
def foo(obj, isinstance=isinstance, str=str):
Some digging turned up an old tracker issue (13 yrs ago) that claimed a big speedup from “using default arguments to take a snapshot of the global functions and constants used by these functions. This transforms accesses to global variabls into local variable access, i.e.
LOAD_FAST instead of
LOAD_GLOBAL virtual machine opcodes”.
Is/was this hooey, and if not, is it still valid given a lot of time has passed and we’re fully into a new major Python version?