Determine whether the unique best‐match alternative is constructible.
Synopsis
Declared in <bslstl_variant.h>
template<
class t_VARIANT,
class t_TYPE,
size_t t_INDEX = BloombergLP::bslstl::Variant_ConvertIndex<t_TYPE, t_VARIANT>::value>
struct Variant_IsAlternativeConstructibleFrom
: bsl::integral_constant<bool, Variant_IsConstructible<typename bsl::variant_alternative<t_INDEX, t_VARIANT>::type, t_TYPE>::value && Variant_HasUniqueCVType<typename bsl::variant_alternative<BloombergLP::bslstl::Variant_ConvertIndex<t_TYPE, t_VARIANT>::value, t_VARIANT>::type, t_VARIANT>::value>Description
This component‐private metafunction is derived from bsl::true_type if there is a unique best match alternative in (template parameter) t_VARIANT for std::declval<t_TYPE>() and that alternative is constructible from std::declval<t_TYPE>(), and bsl::false_type otherwise.
Base Classes
Name |
Description |
Metafunction representing a compile‐time constant of the specified (template parameter) |
Type Aliases
Name |
Description |
Alias for this |
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Alias for the (template parameter) |
Member Functions
Name |
Description |
Return a copy of the template argument |
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Return a copy of the template argument |
Static Data Members
Name |
Description |
The compile‐time constant value of this metafunction. |
Specializations
Name |
Description |
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Derive from |
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