Reusing existing components (objects, subsystems) is a common part of software development. Usually, it is better to reuse an existing solution than rewriting it from scratch, as the latter will inevitably take longer and introduce new bugs.
Using old components in new code, however, brings its own set of problems. Quite frequently, the newer code works against an abstract interface that does not exactly match the existing functionality. We have to write an intermediate object, a kind of translator from the new interface to the old one. This object is called an adapter.
Adapters are used in everyday life. For example, a cable with a USB type A connector on one side and a USB micro connector on the other is an adapter that allows us to plug a mobile phone into a personal computer. Another kind of adapter allows you to plug a device with a German power plug into a UK wall socket, or a device that uses 110 V power into a socket that provides 230 V.
Keep in mind that adapters should...