A closure for "sandboxing" settings.

usage.php

<?php

// usage

withSetting::ini('display_errors', 'off', function() {
   //.. do things
});

withSetting::timezone('America/New_York', function() {
    //.. do things
});

// or if there is a class somewhere
// you can pass args to the method
$class = new SomeClass;
withSetting::timezone($timezone, [$class, $method], $arg1, $arg2, $arg3);

withSetting.php

<?php

class withSetting {
    
    /**
     * Returns a closure bound to the getter and setter of the setting.
     * 
     * @param callable $getter
     * @param callable $setter -- function that accepts one argument
     *
     * @return callable
     */
    public static function withFns($getter, $setter) 
    {
        return function($value, $fn) use($getter, $setter) {
            
            // store and set
            $old_val = $getter();
            $setter($value);

            // reset fn
            $reset = function() use($setter, $value) {
                $setter($value);
            };

            try {
                $args = array_slice(func_get_args(), 2);
                $response = call_user_func_array($fn, $args);
            } catch (Exception $e) {
                $reset();
                throw $e;
            }

            $reset();
            return $response;
        };
    }

    /**
     * Execute a function in a specfiic timezone, it gets set as the default.
     * 
     * @param string $value     the timezone, example UTC
     * @param callable $fn      the continuation
     * @param mixed ...         arguments to pass to the continuation
     *
     * @return mixed            whatever $fn returns
     */
    public static function timezone($value, $fn /*...args*/) 
    {
        $withSetting = self::withFns(
            'date_default_timezone_get', 
            'date_default_timezone_set'
        );

        $args = func_get_args();
        return call_user_func_array($withSetting, $args);
    }

    /**
     * Execute a functino in with a given ini setting
     * 
     * Usage:
     * withSetting::ini('display_errors', 'off', function() { ... });
     * 
     * @param string $name      name of setting for ini_get/ini_set
     * @param mixed $value      the value you want to set it to
     * @param callable $fn      
     * @param mixed ...
     *
     * @return mixed
     */ 
    public static function ini($name, $value, $fn /*...args*/) 
    {
        list($get, $set) = static::iniGetSet($name);
        $withSetting = self::withFns($get, $set);

        // getters and setters bound to name
        $args = array_slice(func_get_args(), 1);
        return call_user_func_array($withSetting, $args);
    }

    /**
     * Usage: list($get, $set) = iniGetSet('display_errors');
     * @param string $name
     * 
     * @return array of closures a getter and setter
     */
    protected static function iniGetSet($name)
    {
        return array(
            function() use($name) {
                return ini_get($name);
            },
            function($v) use($name) {
                ini_set($name, $v);
            }
        );
    }
      
}