A Bridge also serves as an atomic element player in other design patterns. Bridges are scale-independent structures that apply in many object oriented situations. Resulting ContextĪ Bridge is a decoupling of an abstraction (interface) from its implementation so the two can vary independently.

The tight coupling is much easier to manage when all the implementation objects come from the same class, as illustrated in the Codebook example illustrated below. Tight coupling within the Bridge structure is both common and desirable. The workings among the players in a Bridge should be direct and simple: the interface object forwards client requests to the appropriate implementation object. This way each can be varied independently of the other. Separate a class's interface from its implementation by making each a separate but tightly coupled objects. We may need to adapt a class's interface, implementation, or both.ĭecouple an object's public interface ('form') from its implementation (its 'function'), using two (or more) objects where otherwise one might less flexibly suffice.Reuse could mean reuse by other systems that may expect or require a different interface than the one currently provided by our existing class.The existing codebase may constrain what we can do with a class's implementation.How to structure a class so that either (or both) can be easily modified? Forces To achieve reuse, some classes need to adapt either their implementations, their interfaces, or both. perhaps you'd like to choose a specific behavior at run-time.

You anticipate future extensions to object's form or function and you want to avoid extending a class hierarchy for the sake of new implementations. Visual FoxPro operates on dynamic inheritance and instantiates classes directly from a class library or base classes and modify these at run-time.You are designing a new class, or adapting an existing class to make it more reusable. But, generally, most VFP applications talk to SQL Server as well as to its own native database engine.Īs a dynamic object-oriented language, VFP supports multiple class libraries as well as a class browser and is able to provide dynamic subclassing (during run-time) and data dictionary capabilities. Applications developed with VFP are also able to communicate with different database systems such as Oracle, mySQL, SQL Server and many other OLE-DB accessible data sources. Visual FoxPro is used for developing data-centric desktop applications with its own internal database.

Vfp define class