Metafunction that defines type to be the specified t_FALLBACK type unless t_FALLBACK is bslmf::Nil.

Synopsis

Declared in <bslmf_resulttype.h>

template<class t_FALLBACK>
struct ResultType_Fallback;

Type Aliases

Name

Description

type

The fallback type, unless t_FALLBACK is bslmf::Nil.

Specializations

Name

Description

ResultType_Fallback<bslmf::Nil>

Specialization of ResultType_Fallback that does not define type if bslmf::Nil is specified as the fallback parameter.

Derived Classes

Name

Description

ResultType_BdeIdiom

Metafunction to detect the BDE ResultType idiom as part of the implementation of bslmf::ResultType. This struct is instantiated when t_FUNC::result_type doesn't exist. This primary template is matched when t_FUNC::ResultType also does not exist. The t_FALLBACK type, if any, is produced.

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