FOptionA

FOptionA is a named functional option in the FOption family, a lightweight pattern used to configure software components at construction time. It represents a single configurable knob that can be applied by initializer functions to alter behavior without requiring a large parameter list.

In practice, FOptionA is implemented as a small, callable object or function that, when invoked with a reference to a configuration structure, sets one or more fields. It is designed to be composable with other FOption* values, so callers can combine several options to tailor an instance.

Usage typically involves creating an instance with a set of defaults and then applying any provided FOptionA, along with other options, to override defaults. This approach reduces naming collisions and makes defaults explicit while allowing optional customization.

FOptionA often toggles a feature flag or assigns a parameter with a defined value. For example, applying FOptionA could enable a feature A and set a related timeout or threshold, depending on the library's conventions. The exact effect is defined by the component receiving the option.

Compared with fixed constructor arguments, FOptionA and the functional options pattern promote readability and extendability. However, they can require documentation to convey the semantics of each option and may complicate debugging when a large number of options are involved. FOptionA is typically documented as part of a set of related options, along with guidelines for ordering and precedence.

See also functional options pattern, feature flag, configuration management.