let’s say I develop locally and debug small things on live server.
Is it good idea to have something like this in my code? :
$is_local = (strpos($_SERVER['HTTP_HOST'], 'localhost') !== false);
define ('DEBUG',$is_local);
And then use it through my code, when setting stuff?
$mysql_settings = (DEBUG) ?
array(/*localhost settings*/) :
array(/*live settings*/);
This way, I can use the same files live and on localhost, so I can sync without any fear of having wrong e.g. connection settings on live server.
Is it good or wrong idea?
Nothing at all wrong with doing the way you’re doing it.
Another strategy is to set up some environment variable on your development (or other, non-production) system.
Under apache, you could stick something like this:
in httpd.conf or a suitable .htaccess file
Then in your configuration code:
or something along those lines.