Re: how can i short name a compile time state ?

From:
James Kanze <james.kanze@gmail.com>
Newsgroups:
comp.lang.c++
Date:
Wed, 27 Feb 2008 06:44:16 -0800 (PST)
Message-ID:
<73c58398-1da2-4543-9797-795001dddd08@x41g2000hsb.googlegroups.com>
On Feb 27, 7:12 am, toton <abirba...@gmail.com> wrote:

On Feb 25, 1:56 pm, James Kanze <james.ka...@gmail.com> wrote:


    [...]

I'm not too sure what you're trying to achieve. Perhaps
something like:

    template< dir_type >
    struct o_dir ;
    template<>
    struct o_dir< dir_x >
    {
        static dir_type const other = dir_y ;
    } ;
    // etc.

could be used, e.g.:

    template< dir_type dt >
    void
    funct()
    {
        dir_type const od = o_dir::other ;
        dir_type d = o_dir< od >::other ;
        // ...
    }


Hi thanks for the solution. It is working, and this is what I wanted.
However one problem is that , its name causes problem with one of
runtime function defined as,
dir_type o_dir(dir_type dir);
Can I put same name struct and function definition in same
name space, or I need to rename 2 versions as different name.


You can use the same name for both a class and a function in the
same scope, but I wouldn't. It's a hack, present only for
reasons of C compatibility, and will confuse the readers. I'd
come up with some different names. (Generally, the name of a
function should be a verb; the name of a class never is.)

(What i wanted to achieve with this is, one version which returns
orthogonal direction in run time using switch case statement, another
compile time version like const std::size_t dir_x =0; const
std::size_t dir_y = 1;
std::size_t o_dir[] = {dir_y,dir_x}; kind of lookup, except, I wanted
it in terms of enum, where values are not sequential (but finite) ,
and safe. In this version I cant make dir_y = 1000; If I make, 1000
size array is required.


I'm not sure I understand completely, but perhaps some sort of
metaprogramming trick could be used.

--
James Kanze (GABI Software) email:james.kanze@gmail.com
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