Josh Rosenberg added the comment:
BTW, for a realistic use case that would be sped up by this patch (possibly a
lot), consider a recursive function that is continually doing a "virtual" pop
of the first argument, and receiving the rest as varargs, which are then
unpacked for the recursive call, e.g., a function to make a multidimensional
list populated with zeroes:
def nestedzeroes(firstdim, *dims):
'''Make multidimensional list populated with 0s'''
if not dims:
return [0] * firstdim
return [nestedzeroes(*dims) for _ in range(firstdim)]
It's somewhat less artificial in that it multiplies the effect of the
optimization in a way that would actually exercise a microbenchmark-like
scenario, where the amount of work involved in the star-args-only function
calls is an appreciable percentage of the work. Running nestedzeroes(5, 5, 5)
to create a 5x5x5 structure would involve 30 recursive calls; for
nestedzeroes(10, 10, 10), 110 recursive calls.
I've actually used code like this (admittedly rarely) to avoid the hassle of
inlining a many times nested set of list comprehensions to initialize a
multidimensional list.
----------
nosy: +josh.r
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