SEQAN_FUNC_ENABLE

Macro

SEQAN_FUNC_ENABLE_IF

Bind the visibility of a function to an expression.

SEQAN_FUNC_ENABLE_IF(cond, retType)

Include Headers

seqan/basic.h

Parameters

cond	Boolean type. If True or a metafunction that returns True, the following function is visible, otherwise not. Remarks: The boolean value must be available at compile-time, e.g. sizeof(T)>4.
retType	Function return type, e.g. typename Size<T>::Type or void.

Remarks

This macro allows to bind the visibility of a function to a boolean expression by using the SFINAE principle. It can be used in a function declaration/definition instead of its return type. As constructors have no return types, they must be disabled with SEQAN_CTOR_ENABLE_IF.

Examples

template <typename TContainer>
SEQAN_FUNC_ENABLE_IF(
    IsContainer<TContainer>,
    typename Size<TContainer>::Type)
length(TContainer & cont)
{
    SEQAN_CONCEPT_ASSERT((ContainerConcept<TContainer>));
    return end(cont) - begin(cont);
}