Re: templated constanst

From:
"kanze" <kanze@gabi-soft.fr>
Newsgroups:
comp.lang.c++.moderated
Date:
15 Jun 2006 11:02:31 -0400
Message-ID:
<1150355196.519317.184100@y41g2000cwy.googlegroups.com>
Javier Loureiro wrote:

I just read the "limits" header (included with visual 2003),
and it uses the macro :

 #define _STCONS(ty, name, val) static const ty name = (ty)(val)

to declare numeric_limits member variables like has_infinity,
is_integer, etc, inside a struct declaration...

I wrote this simple code using such macro and the limits class
inheritance, and it does not compile...

#define MY_STCONS(ty, name, val) static const ty name = (ty)(val)

namespace mystd {

struct num_base
{
        MY_STCONS(bool, is_bounded, false);
        MY_STCONS(bool, is_exact, false);
};

template <class T>
struct num_procs : public num_base
{
   inline static foo() { return T(0); }
};

struct num_int_base : public num_base
{
        MY_STCONS(bool, is_bounded, false);
        MY_STCONS(bool, is_exact, false);
};

template <> struct num_procs<int> : public num_int_base
{
   typedef int T;
   inline static foo() { return T(20); }
};


What's the error message? I see an obvious error in the fact
that you don't declare a return type for the functions foo(),
but that error should be clear from the error message. The rest
seems OK at first glance.

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James Kanze GABI Software
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