small question, is it better to do
$HOST = $_SERVER["HTTP_HOST"];
and use $HOST throughout my web application
OR
is it better to do
define ( "HOST", $_SERVER["HTTP_HOST"] );
and use HOST throughout my entire web application
OR
is it better to forget using variables and constants and just use $_SERVER["HTTP_HOST"]; every time I need the host?
Which ways more efficient. Which ways more readable.
Which way should I use?
Its better for you use second one,
define ( "HOST", $_SERVER["HTTP_HOST"] );
define it and use it anywhere..
Don't go for third one at any case, because hard coding will affect a lot in future.
The less global variables you have the better, IMHO so just use $_SERVER["HTTP_HOST"] in all of your application. If you really want to define it
define ( "HOST", $_SERVER["HTTP_HOST"] );
is the way to go
Global state is normally bad, since it couples components, breaking the IoC concept.
I would use dependency injection to pass parameters between classes and modules.
But if you really want to use a global variable, why don't you just use $_SERVER["HTTP_HOST"]?
Better is a relative term. Using $_SERVER["HTTP_HOST"] is perfectly acceptable, since everyone looking at it instinctively knows what it's supposed to be and not have to guess if that contains a complete URL or otherwise.
Even if you have to spoof a production hostname for testing, you can still do so with $_SERVER['HTTP_HOST'] = 'www.mywebsite.whatever';