These templates seem to be hard to get right. I guess with experience they get easier to write and comprehend. Anyways, thanks for the explanation.
On Wed, Jul 28, 2010 at 4:44 PM, Philippe Sigaud <[email protected]>wrote: > On Wed, Jul 28, 2010 at 05:50, Andrej Mitrovic <[email protected] > > wrote: > > I won't comment on the double/float issue, I do not anything about it. > > >> T[] find(T, E)(T[] haystack, E needle) >> if (is(typeof(haystack[0] != needle) == bool)) >> >> T1[] find(T1, T2)(T1[] longer, T2[] shorter) >> if (is(typeof(longer[0 .. 1] == shorter) : bool)) >> >> Also, Andrei, you never explained the if(is()) signature of the second >> templated function. I hope to get some pointers on that. :) >> > > I'll have a try at this one. > As you may know, the is(typeof()) syntax is a way to try to compile an > expression and see if it works. If it works, it has a type, given by typeof > and is(Type) returns true. So the first one is really saying: "Hey compiler, > may I compare an element of haystack (of type T) with an E > In this case, longer is an array. So longer[0] would be an element, a T1. > There is no chance that shorter will match as an element cannot be equal to > an array ... except, of course, if longer is an array of T2[] (T1 == T2[]). > Longer is a T2[][]. That may happen for arrays of strings, strings being > arrays of chars. And I think that's the problem you have in your last unit > test. > > Anyway, he takes longer[0..1] to get a slice, which is a dynamic array, a > T1[] and hence comparable to a T2[]... most of the time. > > As for using ': bool' instead of '== bool' as in the first find(), I don't > think there is any difference in this case. I understand T == U as 'T is the > exact same type as U', whereas T : U is for me "T is a subtype of U". But > then, a subtype of bool is pretty much constrained to be a bool. The T : U > syntax is pretty much only used for classes : if(is(T : MyClass)) is saying > : 'compile this only if T is a subclass of MyClass'. > > > Philippe > > > > , except if longer is in fact >
