[#bsl-enable_shared_from_this]
= xref:bsl.adoc[bsl]::enable_shared_from_this
:relfileprefix: ../
:mrdocs:

This class allows an object that is currently managed by a `shared_ptr` to safely generate a copy of the managing `shared_ptr` object. Inheriting from `enable_shared_from_this<ELEMENT_TYPE>` provides the (template parameter) `ELEMENT_TYPE` type with a member function `shared_from_this`. If an object of type `ELEMENT_TYPE` is managed by a `shared_ptr` then calling `shared_from_this` will return a `shared_ptr<ELEMENT_TYPE>` that shares ownership of that object. It is undefined behavior to call `shared_from_this` on an object unless that object is managed by a `shared_ptr`.

== Synopsis

Declared in `<bslstl_sharedptr.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<class ELEMENT_TYPE>
class enable_shared_from_this;
----

== Description

The intended use of `enable_shared_from_this` is that the (template parameter) type `ELEMENT_TYPE` inherits directly from the `enable_shared_from_this` class template. In the case of multiple inheritance, only one of the base classes should inherit from the `enable_shared_from_this` class template. If multiple base classes inherit from `enable_shared_from_this`, then there will be ambiguous calls to the `shared_from_this` function.

== Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:bsl/enable_shared_from_this/shared_from_this-0a2.adoc[`shared_from_this`] 
| `shared_from_this` overloads
| xref:bsl/enable_shared_from_this/weak_from_this-0e.adoc[`weak_from_this`] 
| `weak_from_this` overloads
|===


== Protected Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:bsl/enable_shared_from_this/2constructor-0a.adoc[`enable_shared_from_this`]         [.small]#[constructor]#
| Constructors
| xref:bsl/enable_shared_from_this/2destructor.adoc[`~enable_shared_from_this`] [.small]#[destructor]#
| Destroy this `enable_shared_form_this`.
| xref:bsl/enable_shared_from_this/operator_assign.adoc[`operator=`] 
| Return `*this`. This object is unchanged. Note that the specified `rhs` is not used.
|===


== Derived Classes

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bdlmt/Signaler_Node.adoc[`Signaler_Node`] 
| Provides the implementation of a signaler. This object has a 1‐1 relationship with the `Signaler`, which has a shared pointer to it. This allows other objects to refer to it via shared and weak pointers. This allows `SignalerConnection` objects to outlive the `Signaler ‐ Signaler_Node` pair, since they can test or lock weak pointers to see if the `Signaler_Node` still exists when they are trying to disconnect themselves.
|===


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