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I can't find an explicit answer on this anywhere, but when you create a child class from an abstract class must you use ALL of the methods that are inside the abstract class in the new child class? Or are these methods just available to the child class to pick and choose?

Consider the following code: <?php error_reporting( E_ALL | E_STRICT ); class staticClass { function staticMethod() { //when called statically from the global scope, this throws a fatal error due to $this echo $this->echoMe . "\n"; } } class dynamicClass { public $echoMe; public function __construct( $echoMe ) { $this->echoMe = $echoMe; } public function thisShouldNotWork() { //calling the staticClass method statically does NOT throw a fatal error as expected, the $this reference inside //staticClass is assumed to be a reference to the current instance of dynamicClass instead staticClass::staticMethod(); } } $a = new dynamicClass( "Hello, World!" ); $a->thisShouldNotWork(); /* The above throws a strict warning BUT STILL PRINTS "Hello, World!" Strict Standards: Non-static method staticClass::staticMethod() should not be called statically, assuming $this from incompatible context in test.php on line 22 Hello, World! */ The aptly named function thisShouldNotWork calls a method statically when that method was not defined as static. Even though the function is called statically, $this exists inside that function and can be manipulated and accessed. However, $this inside of staticClass points to a different class. No inheritance is given by the code, but one class is able to access another's variables using $this. PHP "falls back" to the last valid instance of $this since it's a super-global. Only a strict warning level will tell you that something wacky is going on.