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
