tuple sumlimation

[Pragma]

Bill Baxter wrote:
> Pragma wrote:
>> Kevin Bealer wrote:
>>> Currently, Tuples are sublimated into argument lists.  What do people 
>>> think of using an operator (say, *) to prevent this?  The reason I 
>>> ask is that the current technique makes it hard to pass multiple 
>>> tuples on the same function call.
>>>
>>> I think it's not absolutely required; currently you can pass the 
>>> tuple lengths, let the tuples melt together, and then split them with 
>>> slicing.
>>>
>>> Kevin
>>
>> The only workaround I have used for this is to turn a tuple into a 
>> compile-time "struct" to pass it to another template:
>>
>> import std.metastrings;
>>
>> // use whatever name you want, and add whatever 'member' aliases you 
>> need here
>> template Struct(V...){
>>     alias V Values;
>> }
>>
>> template MyExample(alias Arr1,alias Arr2){
>>     pragma(msg,Format!("%s",Arr1.Values[0]));
>>     pragma(msg,Format!("%s",Arr2.Values[0]));
>> }
>>
>> alias MyExample!(Struct!(1,2,3),Struct!("x","y","z")) Foobar;
> 
> Nice idea!  But do you mean
> 
> struct Struct(V...) {
>    alias V Values;
> }
> ???  Otherwise Struct is just making a Tuple.  Or is the trick the fact 
> that you pass it as an alias to the template that needs two Tuples?

Yes.  The trick is indeed the use of "alias"; it allows you to pass the template's namespace just as you would any other 
instanced type.  AFAIK, you can't just pass a tuple to an alias param, so you need to wrap it first.

-- 
- EricAnderton at yahoo