<?php

/**
 * The static members defined in this class, pertaining
 * to the options, are required by several classes to
 * manage default, static, and instance configuration
 * options, each overriding the last respectively.
 *
 * The instance method is just an example.
 */
class Options{

    private $_options = array();
    private $_options_defaults = array(
        'flag_foo' => true,
        'flag_bar' => true,
    );

    public function setOption($name, $value){
        static::$_options[$name] = $value;
    }

    public function setOptions(Array $options, $merge = true){
        if($merge){
            static::$_options = array_replace(static::$_options, $options);
        }else{
            static::$_options = $options;
        }
    }

    public function getOption($name){
        if(isset(static::$_options[$name])){
            return static::$_options[$name];
        }
        if(isset(static::$_options_defaults[$name])){
            return static::$_options_defaults[$name];
        }
        return null;
    }

    public function getOptions(){
        return array_replace(static::$_options_defaults, static::$_options);
    }

    public function useCaseOfClassWithOptions(Array $options = array()){
        $options = array_replace(static::getOptions(), $options);
        if(true === $options['flag_foo']){
            // do the foo
        }
        if(true === $options['flag_bar']){
            // do the bar
        }
    }
}

class ClassThatNeedsOptions {

    private $options;

    public function __construct(Options $options) {
        $this->options = $options;
    }

    public function useCaseOfClassWithOptions(Array $options){
        $options = array_replace($this->options->getOptions(), $options);
        if(true === $options['flag_foo']){
            // do the foo
        }
        if(true === $options['flag_bar']){
            // do the bar
        }
    }
}

new ClassThatNeedsOptions(new Options);