Question

I know that this is a real stupid question, but I don’t really understand something, I use them everyday, but I’m not sure how they work.

class Bootstrap
{
public static $frontController = null;
public static $root = '';

What’s the diff between public static, protected, public…all of them? and when it’s best to use each of one…

Best Regards

Answer 1

• static means the value is accessed via self::$var instead of $this->var, is not instance-specific (i.e. it’s also available in static methods) and thus ideal for singletons and similar patterns
• a public var is accessible from everywhere, i.e. both from inside the class and outside
• a protected var is only accessible from inside the class and from classes inheriting from the class where the var is defined
• a private var is only accessible from inside the class

Since you are asking about OOP basics, here are some more keywords worth explaining:

• an abstract class cannot be instantiated but only used as a base class; a class containing abstract methods must be abstract and a class inheriting from an abstract class must be abstract unless all abstract methods of the base class are actually implemented
• a final class cannot be inherited from