Interface Implicit

• Interaces are satisfied implicitly.
• User defined data types just need to possess the methods defined in interface to be considered an instance of interface.
• We are not locking us with abstration at the start of a project.
• We can define interfaces as and when abstractions become apparent.
• This design lets us create new interfaces that are satisfied by existing concrete types, without changing the existing types.
• Interface definition and concrete type definition could appear in any package without prearrangement(預先做妥的安排).
• It makes it easier to abstract dependencies.

conventional

• Keep interfaces simple and short.
• Define interfaces when there are two or more concrete types that mush be dealt(處理) with in a uniform way.
• Create smaller interfaces with fewer, simpler methods. ask only for what is needed