[#BloombergLP-balm-CategoryHolder]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/balm.adoc[balm]::CategoryHolder
:relfileprefix: ../../
:mrdocs:

This class, informally referred to as a "category holder" (or simply "holder"), holds a category, an enabled value, and a pointer to a "next" holder. Both the category and next pointer may be null. The intended use is as follows: (1) instances of this class are (only) declared in contexts where collecting a metric occurs; (2) if the enabled value is true, the category contains the address of a valid, enabled, category; (3) if the next pointer is non‐null, then the holder pointed to holds the same category and threshold. Instances of this class must be _statically_ initializable. Hence, the data members are `public`, and no constructors or destructor are defined.

== Synopsis

Declared in `<balm_category.h>`

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

== Description

This class should _not_ be used directly by client code. It is an implementation detail of the `balm` metric collection system.

== Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/balm/CategoryHolder/category.adoc[`category`] 
| Return the address of the non‐modifiable category held by this holder.
| xref:BloombergLP/balm/CategoryHolder/enabled.adoc[`enabled`] 
| Return `true` if `category` is valid (i.e., non‐null) and enabled, and `false` otherwise.
| xref:BloombergLP/balm/CategoryHolder/next.adoc[`next`] 
| Return the address of the modifiable holder pointed to by this holder.
| xref:BloombergLP/balm/CategoryHolder/reset.adoc[`reset`] 
| Reset this object to its default value. The default value is: ` { false, 0, 0 } `
| xref:BloombergLP/balm/CategoryHolder/setCategory.adoc[`setCategory`] 
| Set the address of the category held by this holder to the specified `category`.
| xref:BloombergLP/balm/CategoryHolder/setEnabled.adoc[`setEnabled`] 
| Set the `enabled` state of this category to the value of the specified `enabledFlag`.
| xref:BloombergLP/balm/CategoryHolder/setNext.adoc[`setNext`] 
| Set this holder to point to the specified `holder`.
|===


== Data Members

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/balm/CategoryHolder/d_category_p.adoc[`d_category_p`] 
| Address of the held category (not owned).
| xref:BloombergLP/balm/CategoryHolder/d_enabled.adoc[`d_enabled`] 
| Whether the held category is enabled.
| xref:BloombergLP/balm/CategoryHolder/d_next_p.adoc[`d_next_p`] 
| Next category holder in the linked list.
|===



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