[#BloombergLP-balb-ControlManager-registerUsageHandler]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/balb.adoc[balb]::xref:BloombergLP/balb/ControlManager.adoc[ControlManager]::registerUsageHandler
:relfileprefix: ../../../
:mrdocs:

Register a HELP handler that prints usage documentation&period;

== Synopsis

Declared in `&lt;balb&lowbar;controlmanager&period;h&gt;`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
int
registerUsageHandler(std::ostream& stream);
----

== Description

Register a handler that, on receipt of a (case&hyphen;insensitive) &quot;HELP&quot; message, prints to the specified stream a list of this `ControlManager`s registered commands and their documentation&period; Return a positive value if an existing callback was replaced, return 0 if no replacement occurred, and return a negative value otherwise&period;

== Return Value

positive if replaced, 0 if new, negative otherwise

== Parameters

[cols="1,4"]
|===
| Name| Description
| *stream*
| output stream to which usage is printed
|===


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