Overhauling the notion of output range

[Andrei Alexandrescu]

On 07/12/2010 07:44 AM, Steven Schveighoffer wrote:
> On Mon, 12 Jul 2010 02:21:25 -0400, Andrei Alexandrescu
> <SeeWebsiteForEmail at erdani.org> wrote:
>
>> On 07/12/2010 12:45 AM, Philippe Sigaud wrote:
>>> On Mon, Jul 12, 2010 at 03:17, Andrei Alexandrescu
>>> <SeeWebsiteForEmail at erdani.org <mailto:SeeWebsiteForEmail at erdani.org>>
>>> wrote:
>>>
>>> In related news, there's been this burning desire regarding a
>>> lightweight output range defined as simply a delegate that accepts
>>> const(char)[]. That range is an output range all right, and the way
>>> you output to it is by simply calling the delegate!
>>> <http://www.dsource.org/projects/phobos/browser/trunk/phobos/std/range.d#L227>
>>>
>>>
>>> http://www.dsource.org/projects/phobos/browser/trunk/phobos/std/range.d#L227
>>>
>>>
>>>
>>> It's still early where I live, but... For the callable case, why just
>>> accepting E[] instead of any range with E as element? Though, thinking
>>> about it, I right now have no idea how to put that into a template
>>> constraint, given only R and E.
>>>
>>> Hmm...
>>
>> Good point. I haven't thought of it that way - I used arrays as a
>> lingua franca buffer. Your suggestion is interesting. I see a risk of
>> infinite regression in writing the constraint, but the idea warrants
>> more discussion.
>
> Wait, isn't a delegate that accepts a type T an output range of type T?
> Why does the argument have to be an array/range?

Efficiency - see the doFormat disaster.

> For example, a delegate that accepts a string is a range of strings, is
> it not? Or do you consider it a range of immutable(char)?

Good call. Probably I need to handle ranges of arrays differently. (The 
problem has already come up, but I punted on it.)

> For example, I'd expect to be able to use a push_back delegate on an
> array-type of integers as an output range.

Would it hurt to define push_back for arrays too? The thing is, if you 
can output an array you can always output one occasional element. But if 
you only know how to output an element, having the client side output 
arrays in a loop can be quite slow.


Andrei