2015-07-02 17:23 GMT+02:00 Ethan Furman <ethan@stoneleaf.us>:

On 07/02/2015 08:16 AM, Pierre Quentel wrote:

Again, this does not address the original problem : it produces the first 10 squares of 2, not the squares of 2 lower than a "stop" value.

The logic of range(start, stop, step) is to produce the integers starting at "start", incremented by "step", until the integer is >= "stop" (or <= stop if stop<start).

The other logic of range is to be able to say:

some_value in range(start, stop, step)

If step is an integer it is easy to calculate whether some_value is in the range; if step is a function, it becomes impossible to figure out without iterating through (possibly all) the values of range.

It's true, but testing that an integer is a range is very rare : the pattern "if X in range(Y)" is only found once in all the Python 3.4 standard library (in Lib/test/test_genexps.py), and "assert X in range(Y)" nowhere, whereas "for X in range(Y)" is everywhere.

So even if __contains__ must iterate on all the items if the argument of step() is a function, I don't see it as a big problem.

--
~Ethan~

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