[Boost-users] Detecting Valid Expressions for a Type at Compile-Time

From: Martin Ecker (martin.ecker_at_[hidden])
Date: 2007-07-22 00:08:11

Hi,

Is there a way, using SFINAE tricks and potentially the techniques 
used in the Boost Concept Check Library, to detect at compile-time if 
a type T supports a certain expression? In my case, I'm interested if 
T supports operator ==. So I'm basically looking for a compile-time 
predicate so that this compiles:

struct my_struct { int i; };
struct my_struct2 { int i; };
bool operator == (my_struct2 const&, my_struct2 const&) const;

BOOST_STATIC_ASSERT((supports_comparison_operator<int>::value));
BOOST_STATIC_ASSERT((!supports_comparison_operator<my_struct>::value));
BOOST_STATIC_ASSERT((supports_comparison_operator<my_struct2>::value));

Thanks,
Martin