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

This class, informally referred to as a "category holder" (or simply "holder"), holds a category, a threshold level, 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 logging occurs; (2) if the held category is non‐null, then the held threshold is the numerical maximum of the four levels of that 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 automatically generated constructors and destructor are used.

== Synopsis

Declared in `<ball_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 `ball` logging system.

== Enums

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/ball/CategoryHolder/_04enum.adoc[`Unnamed enum`] 
| This enumeration defines distinguished values for category holder threshold levels. Note that these values are intentionally outside the range `[0 .. 255]`.
|===


== Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/ball/CategoryHolder/category.adoc[`category`] 
| Return the address of the non‐modifiable category held by this holder.
| xref:BloombergLP/ball/CategoryHolder/next.adoc[`next`] 
| Return the address of the modifiable holder held by this holder.
| xref:BloombergLP/ball/CategoryHolder/reset.adoc[`reset`] 
| Reset this object to its default value. The default value is: ` { e_UNINITIALIZED_CATEGORY, 0, 0 } `
| xref:BloombergLP/ball/CategoryHolder/setCategory.adoc[`setCategory`] 
| Set the address of the category held by this holder to the specified `category`.
| xref:BloombergLP/ball/CategoryHolder/setNext.adoc[`setNext`] 
| Set this holder to point to the specified `holder`.
| xref:BloombergLP/ball/CategoryHolder/setThreshold.adoc[`setThreshold`] 
| Set the threshold level held by this holder to the specified `threshold`.
| xref:BloombergLP/ball/CategoryHolder/threshold.adoc[`threshold`] 
| Return the threshold level held by this holder.
|===


== Data Members

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/ball/CategoryHolder/d_category_p.adoc[`d_category_p`] 
| Held category (not owned).
| xref:BloombergLP/ball/CategoryHolder/d_next_p.adoc[`d_next_p`] 
| Next category holder in the linked list.
| xref:BloombergLP/ball/CategoryHolder/d_threshold.adoc[`d_threshold`] 
| Threshold level held by this holder.
|===


== Non-Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/ball/ball_log_getCategoryHolder.adoc[`ball_log_getCategoryHolder`]
| Return the address of the specified `categoryHolder`. Note that this function facilitates consistent lookup of block‐scope and class‐scope category holders (see "Logging Macro Reuse" in the "IMPLEMENTATION NOTES" of the component implementation file for details).
|===


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