wrong isInputRange design

[lobo via Digitalmars-d]

On Saturday, 3 December 2016 at 17:29:47 UTC, rumbu wrote:
> On Saturday, 3 December 2016 at 16:37:21 UTC, Jerry wrote:
>> On Saturday, 3 December 2016 at 11:52:00 UTC, rumbu wrote:
>>>[...]
> [...]
>>> [...]
>>
>> Is that the exact code? isInputRange checks to see if the type 
>> has "front" defined.
>
>>
>> https://github.com/dlang/phobos/blob/v2.072.0/std/range/primitives.d#L162
>>
>> Also "string" is just an alias of an array, 
>> "immutable(char)[]". So an array should have "front" defined. 
>> Can you post more code?
>
> No, an array should not have "front" defined according to D 
> language specification. "front" for arrays is defined in 
> std.range.primitives. That's the problem, I cannot have two 
> specialized functions (one taking arrays and one taking 
> ranges), because std.range.primitives hijacks any char array 
> and transforms it in a range). front, empty, popFront must not 
> be defined for arrays in the same module as isInputRange.
>
> Exact code is irrelevant, but you're welcome:
>
> string constructor: 
> https://github.com/rumbu13/numerics/blob/master/src/numerics/fixed.d#L978
>
> range constructor
> https://github.com/rumbu13/numerics/blob/master/src/numerics/fixed.d#L1104

This works for me when specialising for input ranges, strings and 
arrays.

auto f(T)(T val)
     if(isInputRange!T && !isSomeString!T && !isArray!T) {}

auto f(T)(T val)
     if(isSomeString!T) {}

auto f(T)(T val)
     if(isArray!T && !isSomeString!T)

bye,
lobo