ZEND PHP 5 Certification STUDY GUIDE

126 ” Object Oriented Programming in PHP
don’t actually have a body—that’s one of the requirements of abstract classes—and
how the class itself must be declared as abstract in order for the compiler to satisfy
the parser’s syntactic requirements. We then extend DataStore_Adapter into
PDO_DataStore_Adapter, which is no longer abstract because we have now provided
a body for both insert() and update().
Interfaces
Interfaces, on the other hand, are used to specify an API that a class must implement.
This allows you to create a common “contract” that your classes must implement in
order to satisfy certain logical requirements—for example, you could use interfaces
to abstract the concept of database provider into a common API that could then be
implemented by a series of classes that interface to different DBMSs.
Interface methods contain no body:
interface DataStore_Adapter {
public function insert();
public function update();
public function save();
public function newRecord($name = null);
}
class PDO_DataStore_Adapter implements DataStore_Adapter {
public function insert()
{
// ...
}
public function update()
{
// ...
}
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public function save()
{
// ...
}
public function newRecord($name = null)
{