Variadic templates would help implement:

http://all-technology.com/eigenpolls/dwishlist/index.php?it=28

because each tuple type could be expressed as a template:

tuple!(T1,T2,...,Tn) some_function(A1,A2,...,Am)

where T1,..,Tn are the result types, and A1,...,Am are the argument types to some function, some_function.

Thus, the dwishlist example above:

int,int getPoint();

could be expressed:

tuple!(int,int) getPoint();

boost tuple already has this:

http://www.boost.org/libs/tuple/doc/tuple_users_guide.html#tuple_types

In article <dir2ns$28pb$1@digitaldaemon.com>, cppljevans@cox-internet.com says...
>
>Variadic templates would help implement:
>
>http://all-technology.com/eigenpolls/dwishlist/index.php?it=28
>
>because each tuple type could be expressed as a template:
>
>tuple!(T1,T2,...,Tn) some_function(A1,A2,...,Am)
>
>where T1,..,Tn are the result types, and A1,...,Am are the argument types to some function, some_function.
>
>Thus, the dwishlist example above:
>
>int,int getPoint();
>
>could be expressed:
>
>tuple!(int,int) getPoint();

I'm fairly certain that tuples can be implemented in D right now.  I agree that variadric templates would be a very nice feature however.  This has come up in the past and Walter seemed to like the idea, so it will probably happen eventually.


Sean

On 10/15/2005 11:34 AM, Sean Kelly wrote:
> In article <dir2ns$28pb$1@digitaldaemon.com>, cppljevans@cox-internet.com
> says...
[snip]
>>because each tuple type could be expressed as a template:
>>
>>tuple!(T1,T2,...,Tn) some_function(A1,A2,...,Am)
>>
>>where T1,..,Tn are the result types, and A1,...,Am are the
>>argument types to some function, some_function.

Well, actually, what I was looking for was something like
boost's mpl::vector or mpl::list.  Any tuple (or variant)
could then be created with a combination of mpl::vector
and mpl::fold.

[snip]
> I'm fairly certain that tuples can be implemented in D right now.  I agree that

Does anybody have some sample code I could view?

> variadric templates would be a very nice feature however.  This has come up in
> the past and Walter seemed to like the idea, so it will probably happen
> eventually.

Can't wait.  The way boost did it was with help of the Boost
preprocessor library and, IIRC, some special class value
to signal the end of valid template arguments.  They also
did some preprocessing to generate header files.  Anyway,
it was pretty confusing to me, and I thought if D had
a better way, I'd be very happy!

On 11/04/2005 08:03 AM, Larry Evans wrote:
[snip]
>> variadric templates would be a very nice feature however.  This has come up in
>> the past and Walter seemed to like the idea, so it will probably happen
>> eventually.
Doug Gregor patched g++ to implement variadic templates:

http://archives.free.net.ph/message/20060926.213635.0a8fa8a2.en.html

Maybe Doug's implementation would give Walter some howto ideas.

"Larry Evans" <cppljevans@cos-internet.com> wrote in message news:efokmo$1det$1@digitaldaemon.com...
> On 11/04/2005 08:03 AM, Larry Evans wrote:
> [snip]
>>> variadric templates would be a very nice feature however.  This has come
>>> up in
>>> the past and Walter seemed to like the idea, so it will probably happen
>>> eventually.
> Doug Gregor patched g++ to implement variadic templates:
>
> http://archives.free.net.ph/message/20060926.213635.0a8fa8a2.en.html
>
> Maybe Doug's implementation would give Walter some howto ideas.

I'm not into metaprogramming, but I think this would be a great feature of D to pick up.

Already I'm noticing some D templates doing the same copy-paste trick to get a template to accept any number of parameters (like in the S&S examples in the respective thread). IIRC the was another D template library that actually used a D program/script to generate its .d files for any number of parameters! Surely we can do better than that...

L.

Lionello Lunesu wrote:
> "Larry Evans" <cppljevans@cos-internet.com> wrote in message news:efokmo$1det$1@digitaldaemon.com...
>> On 11/04/2005 08:03 AM, Larry Evans wrote:
>> [snip]
>>>> variadric templates would be a very nice feature however.  This has come up in
>>>> the past and Walter seemed to like the idea, so it will probably happen
>>>> eventually.
>> Doug Gregor patched g++ to implement variadic templates:
>>
>> http://archives.free.net.ph/message/20060926.213635.0a8fa8a2.en.html
>>
>> Maybe Doug's implementation would give Walter some howto ideas.
> 
> I'm not into metaprogramming, but I think this would be a great feature of D to pick up.
> 
> Already I'm noticing some D templates doing the same copy-paste trick to get a template to accept any number of parameters (like in the S&S examples in the respective thread). IIRC the was another D template library that actually used a D program/script to generate its .d files for any number of parameters! Surely we can do better than that...
> 
> L. 

That is pretty great.
Though I would prefer some sort of "static foreach" kind of construct rather than having to go purely functional to use the feature.

--bb