实现可配置的工厂模式

Question

Existing Implementation:

I have implemented factory pattern for DB connection. I am having three DB like sql,oracle and sybase. All three classes like sqlConnector,OracleConnector and SybaseConnector has implemented in Iconnect interface and in the factory method i have created the object of these concrete classes(sqlConnector,OracleConnector and SybaseConnector) based on switch case and returned specific object.

Scenario:

I want to modify this factory pattern and want to remove all switch case from factory method and want to configure through config file/xml and also without using reflection and spring.net. Suppose tommorow i introduce new db type , i don't want to change the code.I will make entry in the config/xml ,it should returned the object to client without changing factory.

Question:

How i can implement configurable factory pattern means suppose tomorrow introducing new db type like "MySql", i don't want to change the code of factory.

Answer 1

This is a very broad question, but I think that the technology that will best serve you is Managed Extensibility Framework , or MEF.

MEF is an integral part of .NET that allows you to include additional components into your solution without having to know what those components are beforehand . MEF automatically discovers and includes components into your solution after your solution is built.

You define the points where your solution can be extended; each component is written to take advantage of those extensibility points; MEF ties them together automatically.

If you have used an Inversion of Control framework, like a Dependency Injection library (Ninject, Castle Windsor, SimpleInjector, etc.), then you have already done something a little like this, and the concepts should be somewhat familiar to you.

Explaining it and showing you how to use it will take a book. However, I'm reasonably certain that it will solve your problem best. There are books, blogs, videos, and many, many examples.