On Thu, Dec 11, 2008 at 4:05 PM, saotome <[email protected]> wrote:
> Hi,
>
> can someone tell me how can i check whether a type is comparable ? Is there
> something like "IComparable" in C# ?
It's not entirely a replacement, but you can use some static checking
to make sure that comparison between two types makes sense using is()
and typeof():
int cmp3(T, U)(T a, U b)
{
// is(typeof(a < b)) will only evaluate 'true' if a can be compared to b
static assert(is(typeof(a < b)), "ack, can't compare types '" ~
T.stringof ~ "' and '" ~ U.stringof ~ "'");
if(a < b)
return -1;
else if(a > b)
return 1;
else
return 0;
}
void main()
{
cmp3(3, 4); // fine
cmp3(3, "hello"); // compilation failure
}
However, if you have two Object references and want to see if they're
comparable to one another (i.e. by seeing if they are both instances
of IComparable<Foo> in C#), you're probably out of luck. Thankfully,
most of the time you shouldn't be dealing with Object references
anyway. That's what templates are for :)
