Provide the number of alternatives of a bsl::variant specialization.

Synopsis

Declared in <bslstl_variant.h>

template<
    class t_HEAD,
    class... t_TAIL>
struct variant_size<variant<t_HEAD, t_TAIL...>>
    : bsl::integral_constant<std::size_t, 1 + sizeof...(t_TAIL)>
    , bsl::integral_constant<size_t, 1 + sizeof...(t_TAIL)>

Description

This partial specialization of variant_size provides the number of alternatives, 1 + sizeof...(t_TAIL), for a bsl::variant specialized on (template parameters) t_HEAD, t_TAIL....

Base Classes

Name

Description

bsl::integral_constant<std::size_t, 1 + sizeof...(t_TAIL)>

Metafunction representing a compile‐time constant of the specified (template parameter) t_TYPE with the specified (template parameter) t_VALUE.

bsl::integral_constant<size_t, 1 + sizeof...(t_TAIL)>

Metafunction representing a compile‐time constant of the specified (template parameter) t_TYPE with the specified (template parameter) t_VALUE.

Type Aliases

Name

Description

type

Alias for this integral_constant specialization.

value_type

Alias for the (template parameter) t_TYPE.

Member Functions

Name

Description

operator()

Return a copy of the template argument t_VALUE.

operator t_TYPE

Return a copy of the template argument t_VALUE.

Static Data Members

Name

Description

value

The compile‐time constant value of this metafunction.

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