We want to decouple an abstract entity from its implementation so that each of the two can vary independently.
Handle, Body
You may have an entity you want to define an interface for. This entity, when used will be implemented by each Implementation Classes. Assume that this entity has variations A, B and C of the same property, thus ou will end up with three separate implementations:
- ImplPropertyA,
- ImplPropertyB,
- ImplPropertyC.
Now, consider that we can use these properties, A, B and C, in two different ways - alpha and beta. If we want to display the second dimension of our original entity, we will need to have implementations for each of the possible combinations of Properties (A, B, C) and Methods of usage (alpha, beta). We will have the following implementations:
- ImplPropertyAMethodAlpha
- ImplPropertyBMethodAlpha
- ImplPropertyCMethodAlpha
- ImplPropertyAMethodBeta
- ImplPropertyAMethodBeta
- ImplPropertyAMethodBeta
A better options is to have two hierarchical systems, in which one will be responsible for the properties, while the other will be providing the methods. The Bridge pattern will use the object composition to put all the combinations together depending on client's needs.
