[Python-ideas] Pass a function as the argument "step" of range()
ben+python at benfinney.id.au
Thu Jul 2 08:56:06 CEST 2015
Pierre Quentel <pierre.quentel at gmail.com>
> To achieve the same thing in Python we currently can't use range()
> because it increments by an integer (the argument "step"). An option
> is to build a generator like :
> def gen(N):
> i = 1
> while i<=N:
> yield i
> i *= 2
> then we can iterate on gen(N).
Generators can be defined in expressions, of course::
((x * 2) for x in range(n))
So the full function definition above is misleading for this example.
Your single example defines the ‘step’ function in-line as a lambda
> Iterating on the powers of 2 below N would be done by :
> for i in Range(1, N, lambda x:x*2)
So why not define the generator as an expression::
for i in ((x * 2) for x in range(n)):
That seems quite clear given existing syntax.
Your proposal goes further than that and requires ‘range’ itself to
accept a function argument where it currently expects an integer. But
your example demonstrates, to me, that it wouldn't improve the code.
Do you have some real-world code that would be materially improved by
the change you're proposing?
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