How to define a variable const or static

Question

I'm creating an install page for a web project to define all the config variables and constants before it goes live. I think about keeping those configuration variables in a database but project manager wants them to be kept in a file. So there comes my problem. How do I define these variables, with const or define will work for this job? Example

    <?php
$email_parameter="example@stackoverflow.com"//we need to set this at install.php page and keep it that way
?>

Answer 1

You can use pattern Registry

<?php
/**
* Registry
*/
class Product
{

    /**
    * @var mixed[]
    */
    protected static $data = array();


    /**
     * add value to registry
     *
     * @param string $key
     * @param mixed $value
     * @return void
     */
     public static function set($key, $value)
     {
         self::$data[$key] = $value;
     } 

     /**
      * get value from registry
      *
      * @param string $key
      * @return mixed
      */
      public static function get($key)
      {
         return isset(self::$data[$key]) ? self::$data[$key] : null;
      }

      /**
       * remove value from registry
       *
       * @param string $key
       * @return void
       */
       final public static function removeProduct($key)
       {
           if (array_key_exists($key, self::$data)) {
               unset(self::$data[$key]);
       }
   }
}

/*
 * =====================================
 *           USING OF REGISTRY
 * =====================================
 */

 Product::set('name', 'First product');

 print_r(Product::get('name'));
 // First product

Answer 2

What you need is define

define('__CONSTANT_NAME__', 'example@stackoverflow.com');

Answer 3

define, define('const_name','const_value')

• are everywhere globally available (!),
• are more flexible than const (at least with older PHP versions).

const

• Are (at least in older PHP versions) available only in class definitions.

But

• You cannot define constructs like arrays, objects, etc. (unless you are already using PHP Version 7.
• define's do not honor namespaces (although you could differentiate yourself like this: "ns1/ns2/constant_name"

So, I suggest having your install script writing a config file e.g. config.inc containing define statements for the gathered values. Then let the runtime script(s) include (execute) it: require_once().

If (maybe later) constructs like arrays should be initialised the install script could add these statements too … and much more (even defining classes).

Executing, instead of reading, a config file:

• Main advantage: can contain any executable statements, such as defining and initialising arrays. So, potentially any (even complex) setup constructs are available if needed
• Main disadvantage: is more error prone, since it could fail running when changes introduce syntax errors, and it uses potentially more system resources

At the end I never could measure a big difference between executing and reading config files. And - since the config file is written by an install script, and not modified manually, the aspect of inserting syntax errors is not really important.

Answer 4

Well i checked all your answers and i thank you for that, helped me find the right path for me(at least one that satisfies my "project manager".).I ended up with this solution below:(Those values are for example)

   $f=fopen("config.php","w");
   $database_inf="<?php
     define('DATABASE_HOST', '".$database_host."');
     define('DATABASE_NAME', '".$database_name."');
     define('DATABASE_USERNAME', '".$database_username."');
     define('DATABASE_PASSWORD', '".$database_password."');
     define('ADMIN_NAME', '".$admin_name."');
     define('ADMIN_PASSWORD', '".$admin_password."');
     ?>";
  if (fwrite($f,$database_inf)>0){
   fclose($f);
  }

That is just and example to show how i figured it out. First i created and install php and set default url routing for that page when there is no config file setup. Then i asked the user input realted values and keep them in variables. Finally i created an config file and wirte them in. I hope this can help some oother people who deals similar situation.