Important Software Design Patterns And Their Benefits
A design pattern can be very helpful when it is used in the correct situation and for the correct purpose. They can make the work of a programmer more efficient, and it does so by letting them avoid finding solutions to problems that are fairly common. It is also useful for conceptualizing solutions to problems that are related when there is a discussion with other programmers or the management of the code in a team project is involved. The subject of design patterns has gained some controversy in the world of programming recently because they seem to have become overused. A code that uses different design patterns can lose readability and become difficult for debugging. To make efficient use of design patterns, you should learn how to use them and when is the right time to use them. Let’s look at some design patterns.
Singleton
The singleton design pattern has its use limited for creating a class that will have only one object in the program. This means that a singleton design pattern should be used when one object alone will be able to maintain the coordination between the actions of the entire system. Many examples can fit the use case of a singleton design pattern, it is true in the case of the thread pool, caches and registries.
Initialization of the object of the class is trivial but it is tricky ensuring that only one object is initialized. This can be easily done by making the constructor of the class private while defining a singleton. This means that only the members of the class will have access to the constructor.
The important thing to consider is that there is a possibility of creating a subclass of a singleton by keeping the constructor on the protected part instead of making it private. This can be suitable under certain conditions. A common approach here is making a register of singletons of the sub-class. This will ensure that the getInstance will be able to take a parameter or make use of a variable in the environment for returning the required singleton. The registry will map the names of the strings that are sent to the object of the singleton.
Factory Method
Just as a factory is responsible for the production of goods, the software is responsible for the production of objects. But apart from that, it is also responsible for specifying which class object is being created. For achieving this, functions are called with the help of the factory method instead of making use of a constructor.
It is wrong to make use of the new method for creating an object but it means that the implementation class is tightly coupled with the code itself, which can give rise to some problems.
Strategy
The strategy design patterns make allowance for making groups that are related to algorithms with the help of abstraction. This means that it is easy to switch out an algorithm or policy for another better one without having to modify the client. Instead of making a direct implementation of one algorithm, the code will be given instructions at runtime, which will specify which group of algorithms should be implemented.
Observer
The dependency of this design pattern is one-to-many. This dependency exists between objects, which means that if the state of one object undergoes a change, all the dependents of that object will get notified. This is typically achieved by calling one of the functions.
For simplification, when a user follows another on Twitter, it is essentially asking Twitter to send one user the updates about the tweets of the second person, the person who is being followed. This means there are 2 actors, the one who wants the updates, the observer, and the other who generates these updates, the subject.
A single-subject can have many observers, making it a one-to-many relationship. But the same observer can ask for a subscription and updates of other subjects as well. A subscription for new feeds on Facebook can also be obtained, making the Facebook page the subject, and whenever there is a new post, an update will be sent to the subscribers.
The main thing to be considered here is that many cases will involve numerous subjects but fewer observers. If every subject makes use of separate storage for storing their observers, it will lead to an increase in the amount of storage used and thus its cost, especially because some subjects may keep overlapping observers in their storage.
Builder
A builder design pattern finds its usage in building objects. The objects created can be complex, consisting of numerous sub-objects or an object that requires a process of construction that is very elaborate. The creation of complex types can be made simple with the help of a builder design pattern. An object, whether aggregate or composite, is generally built using a builder design pattern.
It is important to remember that though the builder design pattern may look similar to an abstract factory design pattern, the difference is that the builder design pattern is used for creating objects step-wise, but an abstract factory design pattern will return the entire object as one.
Adapter
The adapter design pattern is used for allowing classes that are incompatible to work together using the interface of one class and converting it into the interface of another. This design pattern can be thought of as a translator, when two people who do not understand a common language meet each other, they need an interpreter with them to translate their conversation, this leading to communication.
If there are 2 separate applications, one whose outs up is in XML and another that requires the input to be in JSON, these two applications will need an adapter design pattern between them so that they can work together efficiently.
State
State design patterns are used for encapsulating different states a machine can be in. It gives the object the allowance to change its behavior when external state changes. Actions can be taken on the context or the machine that will propel it into a different state. Without the help of design patterns, the code or program would not have the flexibility and have numerous if-else statements.
Benefits Of Using Design Patterns
There are many advantages of using design patterns, the code gains robustness, it becomes more readable and there is an increase in reusability. This is mainly because of the fundamental programming problems that are addressed by the use of design patterns, cohesion and coupling.
Coupling is defined as the dependency that exists between the components of a software. It is how the components in the program are interacting, and what degree of their performance is dependent on each other. If the coupling is high, it means that the code is very complex. It can mean difficult maintenance of the code and hence a reduction in its usability. This means that if there is a minor problem encountered by a component, it can cause a disturbance in other components of the program.
The low coupling means that the structure of the code is sound. The code will have robustness, which means that there is a low impact on other components when a change is encountered by one. To achieve a reduction in coupling is difficult, and it can demand a change in the entire program. The rules and methods used for solving issues are defined by design patterns. A software developer can achieve low coupling by following one design pattern from the beginning.
How well a code has been built, and how good it is in doing what it is its intended task, is measured with the help of cohesion. Encapsulation rules dictate that all the data that is related along with associated functions should be in one class. This will ensure that all the functionalities that are related are in one location, and there is a control on their accessibility.
If the cohesion of the code is low, it is indicative that one class is doing several jobs and it is not focused. Having cohesion higher is good because it shows that one is doing a job that is well-defined. To make a program have high cohesion, each class should be given a focused task to work on. Specificity can be increased by separating the tasks that are done by each class.
The use of design patterns will also show its advantages during the testing phase. Generally, a test is conducted by grouped software engineers. A tester will have ease in understanding the flow of a program if they have knowledge of the design pattern used in the code during implementation. A tester will also be able to see the failure of the program on the basis of their experience in the work and their experience working with design patterns. This will equip them with the ability to perform relevant tests.
Those who understand design patterns will be able to communicate and support. Different design patterns have been under discussion in many forums and communities of software developers. A developer can gain help from other software developers when they face some issues. Experienced software developers have trouble describing their work to people with non-technical knowledge. Everyone can be brought to the same page with the help of design patterns. A software developer will be able to visualize the requirements when design patterns are mentioned in the discussion.
Those recruiting for the field of Information Technology are aware of the importance of design patterns. Many recruiters often consider those who have an understanding of correct usage of design patterns to be talented in their field. Development companies who work onsite make use of design patterns in most of their projects, using them to have common elements across their modules. This technique is helpful in removing variability existing in the requirements of the system. This also explains why recruiters are searching for developers who have a deep understanding of design patterns.