[#bsl-optional-07d]
= xref:bsl.adoc[bsl]::xref:bsl/optional-072.adoc[optional<t_TYPE>]
:relfileprefix: ../
:mrdocs:

Deduce the specified type `t_TYPE` from the corresponding template parameter type supplied to the constructor of `optional`. This guide does not participate in deduction unless the deduced type `t_TYPE` supports the bslma allocator model, and the specified `t_ALLOC` can be implicitly converted to `bsl::allocator<char>`.

== Synopsis

Declared in `<bslstl_optional.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<
    class t_TYPE,
    class t_ALLOC>
requires BloombergLP::bslma::UsesBslmaAllocator<t_TYPE>::value && bsl::is_convertible_v<t_ALLOC, bsl::allocator<char>>
xref:bsl/optional-072.adoc[optional<t_TYPE>](
    std::allocator_arg_t,
    t_ALLOC,
    xref:bsl/optional-072.adoc[optional<t_TYPE>]) -> xref:bsl/optional-072.adoc[optional<t_TYPE>];
----


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