Best way to compare primitive types

[John Ohno]

Jari-Matti Mäkelä Wrote:

> Let's say I want to write a wrapper around a primitive type (it could
> possibly also be a class or struct, but that isn't necessary now). What's
> the best way to do opCmp? I've seen there is TypeInfo.compare there
> somewhere, but how does it work? I get
> 
>   Error: this for compare needs to be type TypeInfo not type Foo *
> 
> Also, if it works, does it have performance problems? I read from the ng
> archives that the compiler might not inline it.
> 
> Here's the stuff I'm writing:
> 
> struct Foo(T) {
>         T value;
> 
>         // or maybe T opCmp(T other) for reals, floats etc.
>         // to handle NaN properly
>         int opCmp(T other) {
>                 // I would like to do something like
> 
>                 // return builtin.opCmp(value, other.value);
> 
>                 // because there are so many special cases for
>                 // the primitive types and it feels a bit stupid
>                 // to reimplement the comparison in every wrapper
>         }
> }
You could probably cast to a void[] and opcmp that. Depends on whether you want to compare by value or by pointer.

This should work:

int opCmp!(T)(T o1, T o2) {
        return ((*(cast(void[]*)(cast(void*)o1)))==(*(cast(void[]*)(cast(void*)o2))));
}

It should work for any type, primitive or otherwise.