Add support implicit conversion between types

[Dmitry Olshansky]

06-Sep-2013 21:05, H. S. Teoh пишет:
> On Fri, Sep 06, 2013 at 05:14:48PM +0200, ilya-stromberg wrote:
>> On Friday, 6 September 2013 at 14:26:17 UTC, H. S. Teoh wrote:
>>> I thought the usual D idiom was to write factorial(5) and
>>> factorial(BigInt(5)) and let the compiler figure out which template
>>> instance you wanted?
>>
>> Yes, but it isn't always possible.
>>
>>>> It can be critical for more complex cases, when you call one generic
>>>> function from another one, like this:
>>>>
>>>> unittest
>>>> {
>>>>    alias TypeTuple!(byte, ubyte, short, ushort, int, uint, long,
>>>> ulong, BigInt) IntegralTypeList;
>>>>
>>>>    foreach(T; IntegralTypeList)
>>>>    {
>>>>       assert(factorial!T(3) == 6);//Error: factorial (BigInt
>>>> number)
>>>> is not callable using argument types (int)
>>>
>>> You could just write factorial(T(3)) ?
>>
>> No, I have the error:
>> Error: function expected before (), not byte of type byte
>> Error: function expected before (), not ubyte of type ubyte
>> Error: function expected before (), not short of type short
>> Error: function expected before (), not ushort of type ushort
>> Error: function expected before (), not int of type int
>> Error: function expected before (), not uint of type uint
>> Error: function expected before (), not long of type long
>> Error: function expected before (), not ulong of type ulong
>>
>> As monarch_dodra pointed above, we haven't got "uniform
>> construction" support.
>
> Hmm, I see. This is an unfortunate limitation. In C++, writing int(123)
> actually works. Looks like D is lacking in this area. :-(

I swear I've seen a pull request that enables it.


-- 
Dmitry Olshansky