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

StatusBuilder policy to append an extra message to the original status.

== Synopsis

Declared in `<absl/status/status_builder.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
class ExtraMessage;
----

== Description

This is most useful with adaptors such as `util::TaskReturn` that otherwise would prevent use of `operator<<`. For example:

ABSL_RETURN_IF_ERROR(foo(val)) .With(absl::ExtraMessage("when calling foo()")) .With(util::TaskReturn(task));

or

ABSL_RETURN_IF_ERROR(foo(val)) .With(absl::ExtraMessage() << "val: " << val) .With(util::TaskReturn(task));

Note in the above example, the `ABSL_RETURN_IF_ERROR` macro ensures the `ExtraMessage` expression is evaluated only in the error case, so efficiency of constructing the message is not a concern in the success case.

== Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:absl/ExtraMessage/2constructor-085.adoc[`ExtraMessage`]         [.small]#[constructor]#
| Constructors
| xref:absl/ExtraMessage/operator_call.adoc[`operator()`] 
| Appends the accumulated extra message to `builder`.
| xref:absl/ExtraMessage/operator_lshift-0a.adoc[`operator<<`] 
| Left shift operators
|===



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