Substitution failure is not an error: Difference between revisions

Revision as of 08:30, 2 August 2011

Revision as of 07:07, 9 September 2011

Line 12:

template <typename T>

void f(typename T::type) {} // definitionDefinition #1

template <typename T>

void f(T) {} // definitionDefinition #2

int main() {

f<Test>(10); // callCall #1 .

f<int>(10); // callCall #2. withoutWithout error thanks to SFINAE.

}

</source>

Line 34:

template <typename T>

struct has_typedef_type {

// Variables "yes" and "no" are guaranteed to have different sizes,

// specifically sizeof(yes) == 1 and sizeof(no) == 2.

typedef char yes[1];

typedef char no[2];

Line 45:

static no& test(...);

// ifIf the "sizeof" the result of calling test<T>(0) would be equal to the sizeof(yes),

// the first overload worked and T has a nested type named type.

static const bool value = sizeof(test<T>(0)) == sizeof(yes);