David Abrahams wrote:
// Only the specializations (below) of this template will compile.
template <int N>
static foo
set() { return invalid_value; }
Without a definition for invalid_value, this is invalid code, and on a
conforming compiler, compilation fails at the point it is parsed.
Thanks again. g++ 3.3 appears to happy differentiate between "valid" and
"invalid" enum values with the code below, so allow me to rephrase my
earlier question: which of the two techniques we've discussed would you
use? I assume that one has technical merits over the other?
Regards,
Angus
#include
#include <iostream>
class foo {
public:
enum state {
state1,
state2,
state3
};
// Only the specializations (below) of this template will compile.
template <int N>
static foo
set() { BOOST_STATIC_ASSERT( N == state2 ); }
private:
foo(state)
{
std::cout << "foo" << std::endl;
}
};
template <>
foo foo::setfoo::state2() { return foo::state2; }
template <>
foo foo::setfoo::state3() { return foo::state3; }
int main()
{
// Compiles, as expected.
foo f1 = foo::setfoo::state2();
foo f2(foo::setfoo::state2());
// Fail to compile, as expected.
foo f3 = foo::setfoo::state1();
// foo f4(foo::setfoo::state1());
return 0;
}
