README

Flip is a tiny PHP library for working with strict sets of boolean flags.

• Install via Composer package icecave/flip
• Read the API documentation

Defining a flag-set

A flag-set describes the available flags of a given type. Flag-sets are defined by declaring a class that uses the FlagSetTrait trait.

Each property in the class defines a named flag that can be set to true or false. All properties must be private and have a default boolean value.

use Icecave\Flip\FlagSetTrait;

final class ExampleFlags
{
    use FlagSetTrait;

    private $foo = true;
    private $bar = false;
    private $baz = false;
}

Creating a flag-set

The flag-set trait provides the following static methods for quickly creating common sets:

• defaults() - creates a flag-set where all flags are set to the default values
• all() - creates a flag-set where all flags are set to true
• none() - creates a flag-set where all flags are set to false

Flag-sets can also be created and modified using a fluent interface. The example below creates a flag-set with only the bar and baz properties set to true.

$flags = ExampleFlags::none()
    ->bar(true)
    ->baz(true);

Omitting the initial call to defaults(), all() or none() is short-hand for using the defaults. This means that the following two examples are equivalent:

$flags = ExampleFlags::defaults()
    ->foo(false)
    ->bar(true);

$flags = ExampleFlags
    ::foo(false)
    ->bar(true);

Flag-sets are immutable, each call to the fluent interface returns a new instance with the updated flag value.

Flags can not be named "defaults", "all" or "none".

Using a flag-set

Functions that accept flag-sets as parameters can use a type-hint. Flags are read using the regular PHP property notation. Flag values are guaranteed to be a boolean.

function dumpFlags(ExampleFlags $flags)
{
    if ($flags->foo) {
        echo 'Foo is enabled!';
    } else {
        echo 'Foo is disabled!';
    }

    if ($flags->bar) {
        echo 'Bar is enabled!';
    } else {
        echo 'Bar is disabled!';
    }

    if ($flags->baz) {
        echo 'Baz is enabled!';
    } else {
        echo 'Baz is disabled!';
    }
}

It is not possible to set flags using the property notation.

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