Re: [Boost-users] template int argument

From: Hicham Mouline (hicham_at_[hidden])
Date: 2008-03-18 14:56:26

That's what I thought...

What forbids the compiler from optimizing away the test on n value,
during the template instantiation process?

Thanks,
-----Original Message-----
From: boost-users-bounces_at_[hidden]
[mailto:boost-users-bounces_at_[hidden]] On Behalf Of Steven Watanabe
Sent: 18 March 2008 18:47
To: boost-users_at_[hidden]
Subject: Re: [Boost-users] template int argument

AMDG

Hicham Mouline wrote:
> hi,
>
> I have a template function <typename cT, typename tT, int n>
> {
> ....
> double array[n];
>
> if (n==2)
>   binomial code
> else if (n==3)
>   trinomial code  (array[0] array[1] array[2])
> else
> ....
>
>
> compiler tries to compile the "trinomial code" code even when the template

> is instantiated with n=2,
> and that gives warnings because of array[2]
>
> Is there a way to make the compiler ignore the non-binomial code ?
> rds,

You'll have to split it out into a separate function and use template 
specialization/overload resolution.

template<int n>
void do_n_specific_code(double (&array)[n]);

template<typename cT, typename tT, int n>
void f() {
    double array[n];

    do_n_specific_code(array);

}

In Christ,
Steven Watanabe

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