Template Question

[Bill Baxter]

Mike Parker wrote:
> Bill Baxter wrote:
>> Mike Parker wrote:
>>> Mike Parker wrote:
>>>> Bill Baxter wrote:
>>>>> Mike Parker wrote:
>>>>>> Bill Baxter wrote:
>>>>>>> Mike Parker wrote:
>>>
>>>>
>>>> This is exactly what I was looking for. I don't understand it, but 
>>>> it works.
>>>
>>> Actually, it doesn't work.
>>
>> Ok, so in that case...
>> I think you can put an alias for the type inside an interface, and use 
>> that to work around:
>>
>> interface Foo(T)
>> {
>>     alias T TheType;
>>     void init(T);
>> }
>>
>> ...
>>  static if ( is(U : Foo!(U.TheType)) ) {
>>    ...
>>   }
>>
>> That seems to work.
>>
> 
> Yes, this works. But, the static if evaluation never completes if U does 
> not have TheType. It craps out with errors as soon as U.TheType is 
> encountered rather than printing out the more friendly static assert.

I don't understand.  Can't you just make it

static assert(is(U : Foo!(U.TheType))),
              "Use a Foo!() don't be a Foo! -- Mr. T");

--bb