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Re: Strange range

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Steven D'Aprano <steve@pearwood.info>:

> On Sat, 2 Apr 2016 07:14 am, Marko Rauhamaa wrote:
>> (Somehow, the difference between iterables and iterators is analogous
>> with the difference between C's arrays and pointers.)
>
> I don't understand this analogy. Can you explain please?

In numerous contexts,

   T a[N]

and

   T *a

are interchangeable. In fact, C has no rvalue notation for an array. For
any other type, this works:

   T a, b;
   a = b;

However, if T is an array type, the compiler complains:

   error: assignment to expression with array type

This C innovation of blurring the lines between arrays and pointers is
very different of the type system of Pascal, whose arrays behave like
any other type.

C could have treated arrays like other types without any loss of
generality. Then you'd have to write:

   T a[N], *b;
   b = &a[0];

for:

   T a[N], *b;
   b = a;

Semantically, as well, C arrays are iterables, and pointers are used to
iterate over the elements of an array.

Similarly, Python could have kept iterables and iterators in their
separate corners by specifying:

 * iter(iterable) returns an iterator

 * iter(iterator) typically raises an Exception

 * the for statement requires an iterator

Then, you'd have to write:

   for i in iter([1, 2, 3]):
       ...


Not recommending anything one way or another.


Marko

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Thread

Strange range Marko Rauhamaa <marko@pacujo.net> - 2016-04-01 16:15 +0300
  Re: Strange range Chris Angelico <rosuav@gmail.com> - 2016-04-02 00:24 +1100
  Re: Strange range Steven D'Aprano <steve@pearwood.info> - 2016-04-02 00:26 +1100
    Re: Strange range Marko Rauhamaa <marko@pacujo.net> - 2016-04-01 17:12 +0300
      Re: Strange range Random832 <random832@fastmail.com> - 2016-04-01 10:39 -0400
    Re: Strange range Fabien <fabien.maussion@gmail.com> - 2016-04-01 16:16 +0200
      Re: Strange range Jussi Piitulainen <jussi.piitulainen@helsinki.fi> - 2016-04-01 17:28 +0300
      Re: Strange range Chris Angelico <rosuav@gmail.com> - 2016-04-02 01:31 +1100
        Re: Strange range Marko Rauhamaa <marko@pacujo.net> - 2016-04-01 17:34 +0300
          Re: Strange range Jussi Piitulainen <jussi.piitulainen@helsinki.fi> - 2016-04-01 17:44 +0300
          Re: Strange range Chris Angelico <rosuav@gmail.com> - 2016-04-02 01:45 +1100
            Re: Strange range Marko Rauhamaa <marko@pacujo.net> - 2016-04-01 18:43 +0300
          Re: Strange range Erik <python@lucidity.plus.com> - 2016-04-01 20:58 +0100
            Re: Strange range Marko Rauhamaa <marko@pacujo.net> - 2016-04-01 23:14 +0300
              Re: Strange range Rob Gaddi <rgaddi@highlandtechnology.invalid> - 2016-04-01 20:21 +0000
                Re: Strange range Marko Rauhamaa <marko@pacujo.net> - 2016-04-01 23:44 +0300
              Re: Strange range Steven D'Aprano <steve@pearwood.info> - 2016-04-02 21:09 +1100
                Re: Strange range Marko Rauhamaa <marko@pacujo.net> - 2016-04-02 13:48 +0300
          Re: Strange range Ned Batchelder <ned@nedbatchelder.com> - 2016-04-02 12:47 -0700
            Re: Strange range Marko Rauhamaa <marko@pacujo.net> - 2016-04-02 23:44 +0300
              Re: Strange range Chris Angelico <rosuav@gmail.com> - 2016-04-03 07:05 +1000
                Re: Strange range Marko Rauhamaa <marko@pacujo.net> - 2016-04-03 00:40 +0300
                Re: Strange range Ned Batchelder <ned@nedbatchelder.com> - 2016-04-02 14:50 -0700
                Re: Strange range Stephen Hansen <me+python@ixokai.io> - 2016-04-02 23:43 -0700
                Re: Strange range Marko Rauhamaa <marko@pacujo.net> - 2016-04-03 09:58 +0300
                Re: Strange range Chris Angelico <rosuav@gmail.com> - 2016-04-03 17:10 +1000
                Re: Strange range Ethan Furman <ethan@stoneleaf.us> - 2016-04-03 09:28 -0700
                Re: Strange range Mark Lawrence <breamoreboy@yahoo.co.uk> - 2016-04-04 13:21 +0100
                Re: Strange range Chris Angelico <rosuav@gmail.com> - 2016-04-03 17:08 +1000
              Re: Strange range Steven D'Aprano <steve@pearwood.info> - 2016-04-03 14:43 +1000
                Re: Strange range Random832 <random832@fastmail.com> - 2016-04-03 01:20 -0400
                Re: Strange range Steven D'Aprano <steve@pearwood.info> - 2016-04-03 15:28 +1000
      Re: Strange range Marko Rauhamaa <marko@pacujo.net> - 2016-04-01 17:32 +0300
  Re: Strange range Random832 <random832@fastmail.com> - 2016-04-01 10:42 -0400
  Re: Strange range Chris Angelico <rosuav@gmail.com> - 2016-04-02 01:50 +1100
  Re: Strange range Ian Kelly <ian.g.kelly@gmail.com> - 2016-04-01 08:52 -0600

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