[#bsl-set-0d-emplace]
= xref:bsl.adoc[bsl]::xref:bsl/set-0d.adoc[set]::emplace
:relfileprefix: ../../
:mrdocs:

Emplace a newly constructed `value_type` if not already present.

== Synopsis

Declared in `<bslstl_set.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<class... Args>
xref:bsl/pair-0b.adoc[pair<set<KEY, COMPARATOR, ALLOCATOR>::iterator, bool>]
emplace(Args&&... arguments);
----

== Description

Construct by forwarding `get_allocator()` (if required) and the specified `arguments` to the corresponding constructor of `value_type`; otherwise this method has no effect (other than possibly creating a temporary `value_type` object). Return a pair whose `first` member is an iterator referring to the (possibly newly created and inserted) object in this set whose value is equivalent to that of an object constructed from `arguments`, and whose `second` member is `true` if a new value was inserted, and `false` if an equivalent key was already present. This method requires that the (template parameter) type `KEY` be `emplace‐constructible` from `arguments` (see {Requirements on `KEY`}).

== Return Value

pair of iterator and whether a new element was inserted

== Parameters

[cols="1,4"]
|===
| Name| Description
| *arguments*
| constructor arguments for the new element
|===


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