Option

An option represents a value that may or may not be present. For example, optional values are typically expressed as nullable types ?type, default parameter values, or named arguments with defaults.

Some functional libraries introduce an explicit Option or Maybe type to avoid null references entirely.

By extension, options are possible alternatives to execute a feature. It may tweak the way it is performed, the format of the result, or any other behavior. Such options often have a default configuration which makes them easy to adopt, until the need for specialisation arise.

Options are sometimes used as synonyms as configuration or directive: this is the case when the option has to be provided and has no default. An initial choice must be done.

<?php

// Nullable type: value may be absent
function findUser(?int $id): ?User {
    if ($id === null) {
        return null;
    }
    return User::find($id);
}

// Default value as option
function greet(string $name = 'World'): string {
    return 'Hello, ' . $name;
}

?>

See also Option type.

Related : Named Parameters, Default Parameter, Configuration, Flag, SplSubject