On Friday, 6 September 2013 at 13:50:25 UTC, ilya-stromberg wrote:
On Friday, 6 September 2013 at 13:30:26 UTC, Dicebot wrote:
So, what essentially is needed, is ability to implicitly
convert literals of built-in types to user types, not any
possible implicit conversion?
I think allowing it with such restrictions can be reasonably
clean.
Yes, the ability to implicitly convert literals of built-in
types to user types is REALLY needed.
The 2-nd error from "factorial" example
import std.bigint;
void main()
{
assert(factorial!BigInt(BigInt(3)) == 6); //Error:
incompatible types for ((1) :
(number.opBinary(factorial(number.opBinary(1))))): 'int' and
'BigInt'
}
The correct factorial implementation is:
T factorial(T)(T number)
{
enum T one = 1;
return number <= one ? one : number * factorial!T(number -
one);
}
Or just:
//----
import std.bigint;
T factorial(T)(T number)
{
return number <= 1 ?
T(1) :
number * factorial!T(number - 1);
}
//----
The problem though is that this requires "uniform construction",
which we don't have yet:
http://d.puremagic.com/issues/show_bug.cgi?id=9112
