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

A type‐erased handle for an instance of an Abseil Flag and holds reflection information pertaining to that flag. Use `CommandLineFlag` to access a flag's name, location, help string etc.

== Synopsis

Declared in `<absl/flags/commandlineflag.h>`

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

== Description

To obtain an `absl::CommandLineFlag`, invoke `absl::FindCommandLineFlag()` passing it the flag name string.

Example:

// Obtain reflection handle for a flag named "flagname". const absl::CommandLineFlag* my_flag_data = absl::FindCommandLineFlag("flagname");

// Now you can get flag info from that reflection handle. std::string flag_location = my_flag_data‐>Filename(); ...

== Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:absl/CommandLineFlag/2constructor-0b.adoc[`CommandLineFlag`]         [.small]#[constructor]#
| Constructors
| xref:absl/CommandLineFlag/operator_assign.adoc[`operator=`]  [.small]#[deleted]#
| Not assignable.
| xref:absl/CommandLineFlag/CurrentValue.adoc[`CurrentValue`]  [.small]#[virtual]#
| Returns the current value for this flag.
| xref:absl/CommandLineFlag/DefaultValue.adoc[`DefaultValue`]  [.small]#[virtual]#
| Returns the default value for this flag.
| xref:absl/CommandLineFlag/Filename.adoc[`Filename`]  [.small]#[virtual]#
| Returns name of the file where this flag is defined.
| xref:absl/CommandLineFlag/Help.adoc[`Help`]  [.small]#[virtual]#
| Returns help message associated with this flag.
| xref:absl/CommandLineFlag/IsOfType.adoc[`IsOfType`] 
| Returns true if the flag has type `T`.
| xref:absl/CommandLineFlag/IsRetired.adoc[`IsRetired`]  [.small]#[virtual]#
| Returns true iff this object corresponds to retired flag.
| xref:absl/CommandLineFlag/Name.adoc[`Name`]  [.small]#[virtual]#
| Returns name of this flag.
| xref:absl/CommandLineFlag/ParseFrom.adoc[`ParseFrom`] 
| Sets the value of the flag based on specified string `value`. If the flag was successfully set to new value, it returns true. Otherwise, sets `error` to indicate the error, leaves the flag unchanged, and returns false.
| xref:absl/CommandLineFlag/TryGet.adoc[`TryGet`] 
| Attempts to retrieve the flag value.
|===


== Protected Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:absl/CommandLineFlag/2destructor.adoc[`~CommandLineFlag`] [.small]#[destructor]#
| Destroys this handle. Protected so only derived types may be destroyed.
|===


== Non-Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:absl/FindCommandLineFlag.adoc[`FindCommandLineFlag`]
| Returns the reflection handle of an Abseil flag of the specified name, or `nullptr` if not found. This function will emit a warning if the name of a 'retired' flag is specified.
| xref:absl/GetFlagReflectionHandle.adoc[`GetFlagReflectionHandle`]
| Returns the reflection handle corresponding to specified Abseil Flag instance. Use this handle to access flag's reflection information, like name, location, default value etc.
|===


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