[#absl-Overload-05]
= xref:absl.adoc[absl]::Overload
:relfileprefix: ../
:mrdocs:

`absl::Overload` is a functor that provides overloads based on the functors with which it is created. This can, for example, be used to locally define an anonymous visitor type for `std::visit` inside a function using lambdas.

== Synopsis

Declared in `<absl/functional/overload.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<typename... T>
struct Overload final
    : T...
----

== Description

Before using this function, consider whether named function overloads would be a better design.

Example:

std::variant<std::string, int32_t, int64_t> v(int32_t{1}); const size_t result = std::visit(absl::Overload{ []std::string& s) { return s.size(); }, []auto& s) { return sizeof(s); }, }, v); assert(result == 4);

== Base Classes

[cols="1,4"]
|===
| Name| Description
| `T...`
| 
|===

== Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:absl/Overload-05/2constructor.adoc[`Overload`]         [.small]#[constructor]#
| For historical reasons we want to support use that looks like a function call:
|===


== Using Declarations

[cols="1"]
|===
| Name
| xref:absl/Overload-05/operator().adoc[`operator()`] 
|===


== Deduction Guides

[cols="1,4"]
|===
| Name| Description
| xref:absl/Overload-0a.adoc[`Overload<T...>`] 
| Before C++20, which added support for CTAD for aggregate types, we must also teach the compiler how to deduce the template arguments for Overload.
|===



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