[#BloombergLP-balcl-OptionValue]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/balcl.adoc[balcl]::OptionValue
:relfileprefix: ../../
:mrdocs:

This class implements a special‐use value‐semantic variant type used to represent values parsed from process command lines.

== Synopsis

Declared in `<balcl_optionvalue.h>`

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

== Description

Accordingly, this class can represent values of any of the types defined in `balcl_optiontype`. Furthermore, that value can also be in a null state (defined type but no defined value) to represent allowed options that do not appear among the command‐line arguments (and for which no default value has been configured).

== Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/balcl/OptionValue/2constructor-09.adoc[`OptionValue`]         [.small]#[constructor]#
| Constructors
| xref:BloombergLP/balcl/OptionValue/operator_assign.adoc[`operator=`] 
| Assign to this object the value of the specified `rhs` object, and return a reference providing modifiable access to this object.
| xref:BloombergLP/balcl/OptionValue/allocator.adoc[`allocator`] 
| Return the allocator used by this object to supply memory.
| xref:BloombergLP/balcl/OptionValue/hasNonVoidType.adoc[`hasNonVoidType`] 
| Return `true` if this object is in the unset state, and `false` otherwise. Note that if `false == hasNonVoidType()` then `OptionType::e_VOID == type()`.
| xref:BloombergLP/balcl/OptionValue/isNull.adoc[`isNull`] 
| Return `true` if the value of this object (irrespective of non‐`void` type) is null. The behavior is undefined unless `true == hasNonVoidType()`.
| xref:BloombergLP/balcl/OptionValue/print.adoc[`print`] 
| Write the value of this object to the specified output `stream`.
| xref:BloombergLP/balcl/OptionValue/reset.adoc[`reset`] 
| Reset this object to its default constructed (unset) state. The existing value, if any, is destroyed. Note that on return `OptionType::e_VOID == type()`.
| xref:BloombergLP/balcl/OptionValue/set.adoc[`set`] 
| Set the value of this object to the specified `value`.
| xref:BloombergLP/balcl/OptionValue/setNull.adoc[`setNull`] 
| Set the value of this object, irrespective of that value's type, to its null state.
| xref:BloombergLP/balcl/OptionValue/setType.adoc[`setType`] 
| Set the type of this object to the specified `type` and the value to the default value of that type.
| xref:BloombergLP/balcl/OptionValue/swap.adoc[`swap`] 
| Efficiently exchange the value of this object with the value of the specified `other` object.
| xref:BloombergLP/balcl/OptionValue/the-06.adoc[`the`] 
| `the` overloads
| xref:BloombergLP/balcl/OptionValue/type.adoc[`type`] 
| Return the type of this command‐line‐option value. The type `OptionType::e_VOID` represents the unset state.
| xref:BloombergLP/balcl/OptionValue/2conversion.adoc[`operator BloombergLP::bslmf::NestedTraitDeclaration<OptionValue, HasPrintMethod>`] 
| Nested trait declaration for `bslma::UsesBslmaAllocator`.
|===


== Friends

[cols="1,4"]
|===
| Name| Description
| `xref:BloombergLP/balcl/swap.adoc[BloombergLP::balcl::swap]`
| Swap the value of the specified `a` object with the value of the specified `b` object.
| `xref:BloombergLP/balcl/operator_eq-0d.adoc[BloombergLP::balcl::operator==]`
| Return `true` if the specified `lhs` and `rhs` objects have the same value, and `false` otherwise.
|===

== Non-Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/balcl/operator_not_eq-001.adoc[`operator!=`]
| Return `true` if the specified `lhs` and `rhs` objects do not have the same value, and `false` otherwise.
|===


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