[Python-3000] Making strings non-iterable

[Brett Cannon]

On 4/13/06, Ian Bicking <ianb at colorstudy.com> wrote:
> I propose that strings (unicode/text) shouldn't be iterable.  Seeing this:
>
> <ul>
>   <li> i
>   <li> t
>   <li> e
>   <li> m
>   <li>
>   <li> 1
> </ul>
>
> a few too many times... it's annoying.  Instead, I propose that strings
> get a list-like view on their characters.  Oh synergy!
>
> Thus you would do:
>
>    for c in a_string.chars():
>        print c
>
> This view would have the full complement of list methods (like .count(),
> .index(), etc), and would not have string methods (like .upper()).
>

+1 from me.

I almost suggest a words() view, but with split() I don't know if that
is needed.  Then again split() could possibly go away if there was a
words() view.

-Brett

> Iterating over strings causes frequent hard bugs (bad data, as opposed
> to exceptions which make for easy bugs), as the bug can manifest itself
> far from its origination.  Also strings aren't containers.  Because
> Python has no characters, only strings, as a result strings look like
> they contain strings, and those strings in turn contain themselves.  It
> just doesn't make sense.  And it is because a string and the characters
> it contains are interchangeable (they are both strings) that the
> resulting bugs can persist without exceptions.
>
> Should bytes be iterable as well?  Because bytes (the container) and
> integers are not interchangeable, the problems that occur with strings
> seem much less likely, and the container-like nature of bytes is
> clearer.  So I don't propose this effect bytes in any way.
>
> Questions:
>
> * .chars() doesn't return characters; should it be named something else?
>
> * Should it be a method that is called?  dict.keys() has a legacy, but
> this does not.  There is presumably very little overhead to getting this
> view.  However, symmetry with the only other views we are considering
> (dictionary views) would indicate it should be a method.  Also, there
> are no attributes on strings currently.
>
> * Are there other views on strings?  Can string->byte encoding be
> usefully seen as a view in some cases?
>
> --
> Ian Bicking  /  ianb at colorstudy.com  /  http://blog.ianbicking.org
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