Re: [boost] [Ann] Variadic Templates

From: Douglas Gregor (doug.gregor_at_[hidden])
Date: 2006-10-01 20:17:26

On Oct 1, 2006, at 2:52 PM, Larry Evans wrote:

> On 08/04/2006 04:54 PM, Doug Gregor wrote:
> [snip]
>> I have just completed implementing support for "Variadic  
>> Templates"  in GCC. Variadic templates are C++ templates that can  
>> accept any  number of "extra" template arguments, just like a  
>> function that uses  C-style varargs (with "...") can accept any  
>> number of extra  arguments. Unlike C varags, however, variadic  
>> templates work both for  class templates and function templates,  
>> and are completely type-safe.
> Doug,  I read:
>
>   http://www.osl.iu.edu/~dgregor/cpp/variadic-templates.pdf
>   section 3.2 on p. 8.
>
> and thought I'd try this initialization, but with the attached I got:
>
> /home/evansl/download/gcc/variadic-templates/gcc-4.1.1/install/bin/g 
> ++ -c -Wall -ftemplate-depth-100 -O0 -fno-inline -I/home/evansl/ 
> prog_dev/boost-cvs/ro/boost/sandbox/variadic-templates - 
> I"../../../../.." -I"../../../../../../.."  vinit.cpp  -o vinit.gccv.o
> vinit.cpp:17: error: too many initializers for 'test'
> make: *** [vinit.gccv.o] Error 1
>
> What am I doing wrong?

Well, you're not doing anything wrong. That section of the proposal  
was meant to be a "if the initializer lists proposal is accepted,  
then it would act like this."  I didn't actually mean to propose any  
changes to the initializer syntax, and so I didn't implement them.  
(That said, it's a relatively simple feature to implement, if we need  
it to test something out).

> TIA.  (BTW, this is a great addition to the language!)

Thanks!

        Cheers,
        Doug