Parameterized Structs

[Steven Schveighoffer]

On Thu, 03 Mar 2011 00:45:05 -0500, Bekenn <leaveme at alone.com> wrote:

> On 3/2/2011 8:56 PM, Peter Lundgren wrote:
>> Where can I go to learn about parameterized structs? I can't seem to  
>> find any
>> literature on the subject. In particular, what are you allowed to use  
>> as a
>> parameter? I would like to define a struct like so:
>>
>> struct MyStruct(T, T[] a) {
>>      ...
>> }
>>
>> but I receive the following error:
>>
>> Error: arithmetic/string type expected for value-parameter, not T[]
>>
>> Are arrays not allowed?
>
> This compiles:
>
> 	struct MyStruct(T : T[], T a)
> 	{
> 		T A = a.dup;
> 	}
>
> ...but I have yet to figure out how to properly invoke it.

warning to all template novices -- a template compiling simply means it  
*PARSES*.  You have to instantiate it, in order to verify it is correct.   
The compiler cannot possibly know the semantic meaning of a template  
without knowing what the parameters are.

I would expect your struct to never instantiate properly, because a.dup is  
not a valid static initializer.

-Steve