l = range(int(1E9))

[Ian Kelly]

On Sat, May 2, 2015 at 1:51 PM, BartC <bc at freeuk.com> wrote:
> On 02/05/2015 20:15, Mark Lawrence wrote:
>>
>> On 02/05/2015 19:34, BartC wrote:
>
>
>>> OK, so it's the programmer's fault if as fundamental a concept as a
>>> for-loop ranging over integers is implemented inefficiently. He has to
>>> transform it into high-level terms, or has to reconstruct it somehow
>>> using a while-loop and an incrementing loop index.
>
>
>> I give up.
>
>
> So do I, I think, if no-one is willing to admit that the original way of
> implementing range() was a glaring mistake.

range() was and is a *convenience* function. In the real world, the
vast majority of for loops are over arrays or other containers, not
integers, and those that aren't are usually very small. In non-toy
code, using a for loop to count to a billion is highly unusual.

So yeah, for a programmer porting code to Python who needed to loop
over an array, the correct approach would be to actually loop over the
*array* in place of the indices of the array. I don't know why you
make this out to be such a big deal; it's a simple conversion.

Would it have been better if range() had been implemented as xrange()
from the beginning? Sure, that would have been great. Except for one
small detail: the iterator protocol didn't exist back then. That
wasn't introduced until PEP 234 in Python 2.1, which means that the
xrange() function wasn't even *possible* before then.

I don't think anybody would claim that Python was perfect when it was
first introduced (nor is it perfect now). Like all other software, it
has improved over time as a result of iterative refinement.