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copied!<p>For some reason I found the problem description easy to misunderstand, but the linked code makes it clear. In C++11 it's easy:</p> <pre><code>#define SETUP_ENUM_LENGTH(enum_type, length) \ static constexpr int enum_length(enum_type*) { return length; } </code></pre> <p>and a </p> <pre><code> for (int i = 0; i < enum_length((Enum*)0); ++i) { </code></pre> <p>in the right place. Here's a sample:</p> <pre><code>#include <iostream> #include <functional> #include <boost/preprocessor/variadic/size.hpp> /** * Macro to setup an enum completely. * First parameter is the name, following are the states as plain text. */ #define DEF_ENUM(name, ...) \ enum class name : uint8_t { __VA_ARGS__ }; \ SETUP_ENUM_LENGTH(name, BOOST_PP_VARIADIC_SIZE(__VA_ARGS__)) /** * Once an enum class is defined, this macro makes the size publicly available. * Needed by enum_array. Already included in DEF_ENUM. */ #define SETUP_ENUM_LENGTH(enum_type, length) \ static constexpr int enum_length(enum_type*) { return length; } /** * Function to iterate over all elements of an enum. */ template<typename Enum> void enum_for_each(const std::function<void(Enum e)> &fct) { for (int i = 0; i < enum_length((Enum*)0); ++i) { fct(static_cast<Enum>(i)); } } namespace n { DEF_ENUM(demo,u,v,w,x,y,z,a,b,c); } namespace m { DEF_ENUM(demo,a=3,b=1,c=4,d=1,e=5); } using std::cout; int main() { enum_for_each<n::demo>([](n::demo e) { cout<<int(e); }); cout<<'\n'; enum_for_each<m::demo>([](m::demo e) { cout<<int(e); }); cout<<'\n'; int ndemo[enum_length((n::demo*)0)]; int mdemo[enum_length((m::demo*)0)]; cout << sizeof ndemo << ' ' << sizeof mdemo << '\n'; } </code></pre> <p>As a side note, that <code>static_cast<Enum>(i)</code> looks troublesome, does it really do the right thing with the <code>m::demo</code> enum?</p> <p>To preserve the original templated-<code>enum_length</code> usage and so make the array-allocation usage a bit prettier is easy from here, rename the function <code>enum_length_helper</code> and then</p> <pre><code>template<typename Enum> struct enum_length { enum result=enum_length_helper((Enum*)0); }; </code></pre>

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