Warming up Design Patterns - Part 1

Do I really need to refer Design Patterns for cooking good Food?

Too much I can say too much material available for learning Design Patterns aka DP. But very less article directs us when really we need DP and what’s the know how to implement it. DP are nothing but the well defines and proven approach towards achieving some goal in development. Most of the time it adheres to common features available in various languages, but not constrained to any language as such. DP's are well thought out solution to programming problems. These DP's are not evolved overnight but they are the collections of efforts done by various programmers worldwide.

When each developer writes code, he himself has some way for achieving certain solution to problem. He comes with some solution which itself can be a pattern. But here is the mess who can say that what he did is the best solution, or is the only solution to that problem. Again if this is the simple assignment, then it is fine as we will consider "Result is bottom line". But if this is some framework or part of application that is enterprise and need to be extensible and reusable then, it becomes necessity to check that this solution is a proven solution. Here DP comes handy. It assures that it works. And what if there doesn't exist any pattern that matches our problem, and then might be we are one of them who discovered a new pattern. But stop... it's not yet publishable; you have to verify it and make sure that it will work for all such problems. 

In Conclusion and as disclaimer I will repeat the statement of one of author: "Any design pattern can be a double-edged sword— if implemented in the wrong place, it can be disastrous and create many problems for you. However, implemented in the right place, at the right time, it can be your savior."

Well this is my short J effort to tell what & why DP. Now let’s explore it in more technical way.

Let's cook with Design Patterns

Design patterns are majorly categorized into 3 types depend on where they talk about How to manage types and relation or Creating Object or how the objects are going to communicate with each other to make our design to be scalable with respect of change / addition in underlying algorithms. 

1) Structural: 

These patterns emphasize on relationships between entities. They talk about how classes and objects can be combined to form large systems. Here main thing to note that class and object do differ. Class patterns make use of Inheritance mechanism to provide more useful program interfaces whereas object patterns talks about composing different objects using composition i.e. including object within other object, to achieve the same goal.

2) Creational

These patterns deal with object creation mechanism. The main design goals are how the objects will be created, how the creation of object will be controlled and how to less the impact on client logic when there are frequent changes in the creation logic i.e. decoupling.

3) Behavioral

These patterns more worry about how object should communicate to increase flexibility in communication. It also makes sure the scaling of system with respect to addition/modification in underlying algorithm.

In next part of the article we will elaborate each of these categories in more detail with suitable example.