1. Executive Summary
Design patterns are the
most basic component acknowledged in construction of quality reliable
architectures in software. This report delves into the three main categories of
design patterns: Creative, structural and behavioral; the three categories are
introduced then described and explained in this paper. A group of creational
design patterns like Singleton’s, Factory Method and Abstract Factory patterns
deal with object creation techniques and at the same time introduce flexibility
and extensibility. Structural patterns include Adapter, Decorator and Composite
pattern that deal with the way in which classes and objects are constructed to
meet the most optimal designs of scalable systems. Behavioral patterns include
Observer, Strategy and Command improving system flexibility and
maintainability. Comparing and analyzing the specialties of each pattern
category can ensure the understanding of their use and effectiveness in solving
various design issues. The conclusion re-emphasises the need to be wiser and
intelligent when applying design patterns to be able to come up with better
solutions that will be flexible, scalable and of high quality.
Table of Contents
Table
of Figures
Figure 1: Types of Design Patterns
Figure 2: Code Example: Singleton Pattern
Figure 3: Code Example: Adapter Pattern
Figure 4:Code Example: Observer Pattern
Table
of Tables
Table 1: Creational Design Patterns
Table 2: Structural Design Patterns
Table 3: Behavioral Design Patterns
2.
Introduction
This paper shows that
design patterns are one of the fundamental concepts in the field of software
engineering that offer widely applied practical solutions. Coinage to design
pattern started with the publication of a book by Erich Gamma, Richard Helm, Ralph
Johnson and John Vlissides, famously known as the three authors of “Gang of
Four” design pattern (bin Uzayr, 2022).
They are intended mostly for providing rather universal and abstract solutions
to common issues in the design of software, thereby contributing to the
generation of dependable and comprehensible code. These best practices allow
developers to solve matters of design and development that a project can post
by implementing a set of standards that have been accredited and seen to
perform well over a period. Being an evolution of the current implementations,
design patterns help to achieve a higher level of interaction between the
members of development teams, as these solutions are described in a way that
can be easily understood by everyone. The division of the design patterns into
creation, structural, and behavioral is beneficial in the approach towards the
understanding as well as the usage of these solutions (Micheli et al., 2019).
Figure 1: Types of Design Patterns
In the following section,
this report discusses these three categories and the importance of each group
of the design pattern and the samples in each category of pattern. The purpose
of the report is to give a clear understanding of creational, structural and
behavioural patterns, their utility and advantages for successful software
development.
Creational Design
Patterns
Creational design patterns
are the base of good, structured software systems that are reliable to develop (Rahman et al., 2023). These patterns concentrate on producing adequate items
for the environment in the most optimized production procedures and methods
that are flexible in case of difficulty or change in requirements. Widening of
the instantiation process provided by creational patterns allows code reuse,
improves system flexibility, and the quality of general architectural
solutions. Among the key creational design patterns includes Singleton, Factory
method and Abstract Factory method patterns shift can be provided to look at
different types of object creation and their management (Al-Hawari, 2022).
|
Pattern |
Description |
Use Case |
|
Singleton |
Ensures a class has only one instance and provides a global
point of access |
Logging service, configuration
management |
|
Factory Method |
Defines
an interface for creating objects but allows subclasses to alter it |
When a
class cannot anticipate the type of objects it needs to create |
|
Abstract Factory |
Provides an interface for creating families of related or
dependent objects |
When systems need to be independent of how their products
are created or composed |
Table 1: Creational Design Patterns
The Singleton pattern
belongs to the creational patterns and is one of the most used ones. The main
objective is to make certain that a class has at most one instance and to
simultaneously make that instance globally accessible. This pattern is most
beneficial in situations where exactly one object should be responsible for
managing what is happening in the system, such as in the Configuration
Management or a Log Service. As compared to the normal approach of object
creation and Spoon feeding, the Singleton pattern holds control over object
creation to ensure that it does not create more instances of objects that can
cause inconsistency and conflict over the use of resources. This pattern also
helps in performance optimization since object creation and management are
associated with overhead.
Figure 2: Code Example: Singleton Pattern
The Factory Method
pattern, which belongs to the creational family of patterns, shapes the
interface for creating objects but lets the subclasses change the actual type
of objects to be created. This pattern becomes very useful if a class cannot
know in advance what kinds of objects it is going to create or if the creation
of objects is the responsibility of subsidiaries. The Factory Method pattern
increases the simplicity and adaptability of the application since the client
code communicates only with the interface for the desired objects and depends
on the Factory subclasses that create them. It enables the system to bring in
other classes with little or no changes made on previous code to allow addition
and further modification of the system to the new emerging needs.
The pattern closely
related to the Factory Method is the Abstract Factory pattern, which
offers the interface for creating the families of objects that are related or
dependent on one another. This pattern is particularly useful where the systems
requiring the handling of a large amount of information need to remain free
from the particulars of the product types, they are handling. This pattern
deals with a set of diverse individual factories and shields the clients from
working directly with concrete classes. Such an abstraction ensures that there
is conformity and standardisation where there are related products; hence, they
facilitate the general management and evolution of the system. It is especially
useful when the systems involve several products’ families as the variations
can be quite significant.
Altogether it is necessary
to mention that creational design patterns are the key to ensuring effective and
fast object creation in software systems (Bach et al., 2023). These three types of patterns are interrelated to the
difficulty of object creation and are all efficiently designed to offer
solutions to those design problems. Thus, by using such patterns, developers
can design and implement maintainable, scalable and more adaptable application
systems.
3.
Structural
Design Patterns
This category of design
patterns is crucial in software engineering as it tackles the structural
aspects of classes and objects. These patterns just help the design to indicate
that there exists a simple way to realize relationship among the entities and
will make the structure more flexible. These patterns apply means by which
objects can be composed to form other complex structures with a main aim of
increasing the maintainability, reusability, and scalability of these
applications. Some of these structural patterns include Adapter, Decorator, and
Composite all of which have specific advantages and sought to solve certain structural
issues (Liu et al., 2020).
|
Pattern |
Description |
Use Case |
|
Adaptor |
Allows
incompatible interfaces to work together |
Integrating
legacy systems with new ones |
|
Decorator |
Adds behavior to objects
dynamically without altering their structure |
Extending
functionalities flexibly, such as adding features to a user interface |
|
Composite |
Treats
individual objects and compositions of objects uniformly |
Representing part-whole hierarchies, such as tree
structures |
Table
2: Structural Design Patterns
The adapter pattern is intended to enable two interfaces
that are not compatible for use to engage in an acknowledgement process.
Instead of having to change the entire interface of an existing class, this
pattern can effectively be used to provide a border around a class to make a
new interface compatible. Adapter pattern is applied most effectively when
working with legacy systems and new ones or when a class requires cooperation
with another class but is designed with an incompatible interface. Thanks to
this, by changing the interface of a class into other one client expected, the
Adapter pattern lets classes cooperate without changing their source. This
reusability of classes contributes to facilitating the development of new
systems by using parts of old systems and makes the system more flexible.
Figure 3: Code Example: Adapter Pattern
The Decorator pattern
is another basic structural pattern that enables one to change the behavior of
objects; the change does not affect the behavior of other objects derived from
the same class. This pattern is particularly useful when adding one or more new
functionalities in a versatile manner. The Decorator pattern is applied when
there is a set of decorator classes for wrapping real components. This wrapping
can be done as many times as need be, to make it possible to attempt the
construction of the behavior that is desired. This pattern allows practicing
the open/closed principle, which states that classes should be open for
extension but closed for modification, which, in turn, boosts the system’s
flexibility and maintainability.
The Composite pattern
is meant to make working with individual objects and compositions of objects
very similar. This pattern is suitable when modeling part-whole relationships
such as in trees. The Composite pattern helps the client to keep away from
different types of the composition that work on different levels, making all
the works on objects and the compositions of them similar, which is helpful in
simplifying the client code that works with the complexes of the objects. This
pattern boosts up the structuring by making the system flexible to new
recognisable subclasses with limited alteration to orders of code. It also
enhances the reuse of code as it shows such compositions can be constructed
from complex units.
Structural design patterns
are essential in determining the arrangement of classes and objects in the
software systems. The contextual problems that these patterns solve one by one
are as follows and each of these is well equipped to offer substantial
solutions for structurally integrating intricate and efficient systems (Hukerikar and Engelmann, 2017). These patterns help the developers
in understanding the reoccurring situations and hence the solutions they impose
creates more flexible, scalable and easier to manage software systems.
4.
Behavioral
Design Patterns
Behavioral design patterns belong to the wider category of Software
design patterns, which concern themselves with the practical aspects of the
flow of communication between the various objects. Such patterns assist to
determine the way in which objects work concurrently to execute the task within
the system with more modularity and ease of maintenance. Behavioral patterns
focus on the mechanisms of division of work between objects so that the system
can remain unsophisticated and highly scalable. Observer, Strategy, and Command
are some of the behavioral design patterns depending on aspects of objects (Hussain et al., 2017).
|
Pattern |
Description |
Use Case |
|
Observer |
Establishes
a one-to-many dependency between objects |
MVC
architectures, event handling systems |
|
Strategy |
Defines a family of
algorithms, encapsulates each one, and makes them interchangeable |
Dynamic behavior
changes, such as different sorting algorithms |
|
Command |
Encapsulates
a request as an object |
Parameterizing,
queuing, and logging requests, implementing undo functionality |
Table 3: Behavioral Design Patterns
Observer pattern is one of the frequently used
behavioral patterns as it enables the dependency between the one instance and
many instances. This pattern makes it possible for any observers which are dependent
on the subject to be informed and updated once the state of the object changes.
The Observer pattern becomes useful mostly at those cases when one object
requires to update several others, if its state has changed for example, in the
MVC model. This pattern improves the flexibility and the extensiveness of the
system since by increasing the degree of loose coupling between the subject and
observers, new observers can be included without modifying the existing subject.
Figure 4:Code Example: Observer Pattern
The Strategy pattern
defines a set of algorithms, encapsulates every one of it and ensures that they
can be exchanged. This pattern enables the algorithm to differ from clients
that employ it since it has its alteration cycle. The Strategy pattern is most
useful in a situation where object of a certain class would have to do a
particular job, yet the methods involved or the algorithms to be used may vary.
The Strategy pattern encloses algorithms and makes the system more reusable and
adaptive and allows for switching algorithms without changing the client’s
code. This pattern is typical for situations when the behavior of objects must
be altered throughout the execution, for example, sorting or payment methods.
In the Command pattern,
a request is captured as an object thus it permits clients to be characterized
by different requests, requests can be arranged or recorded as they are logged.
This pattern is well fitting in a situation in which operations must be
performed, rolled back or scheduled. That’s why encapsulation of requests in
the Command pattern frees the object that requests the operation from the one
that knows how to execute it. This separation of concerns results in
flexibility and extensibility, in which the addition of new commands is
improved in a way that doesn’t require changes to previous codes. Most of the
applications can undo a certain action and the Command pattern is the one used
in this case.
All in all, it can be
mentioned that behavioral design patterns are quite important to handle the
object communication and the distribution of tasks in several systems (Kopetz and Steiner, 2022). Thus, such patterns improve the
general quality of software solutions’ architecture and make them more
maintainable by increasing loose coupling, flexibility, and scalability.
Learning these patterns will help developers learn the knowledge about how to
construct better, more convivial and extensible software systems.
5.
Comparison
and Analysis
When comparing and
analyzing the creational, structural, and behavioral patterns, one can conclude
that each of them is dedicated to specific issues of the software design
process and has their advantages and potential problems to solve. To avoid
confusion and get the best results when implementing these patterns in different
development situations, one needs to analyze these patterns knowing their
similarities and differences(Behnam and Zarabadi, 2017).
According to the
possibilities of creational design patterns, it incorporates mostly the process
of creation of objects. These patterns offer ways of creating objects in such a
manner that fits the system’s needs for flexibility and reuse. For example,
Singleton pattern makes sure there is only a single instance of the class which
during instantiation of objects we can use; useful in areas such as logging or
configuration where a single point of access is needed. While in the Factory
Method and Abstract Factory patterns the application declares the creation of
objects, the choice of the concrete class to instantiate is deferred to the
further detailed levels of the implementation, making the application more
flexible and easily scalable. On the other hand, structural design patterns warrant
the organization of classes and objects, thus enhancing the way elements within
a system may be assembled. The Adapter pattern matches the two incompatible
interfaces so that they can work together; this makes it useful when one wants
to interface between old systems and a new part. The Decorator pattern adds
functionality to objects on the fly without the necessity to modify their
structure and it complies with the open/closed principle. Composite pattern
induces a shared interface for objects and compositions meaning that
compositions are treated as objects thus reducing the client code and making
client code’s approach more homogeneous. The behavioral patterns of
object-oriented design deal with the behavior and communication process of the
objects and explain how objects perform a particular task. The Observer pattern
sets up the one-to-many of depends on the subject where all the dependents will
be updated once the state of the subject has changed. The Strategy pattern
encapsulates algorithms; this makes it possible to substitute them with another
one, which is viable where dynamism in behavior is desirable. The Command
pattern is used to wrap requests as objects so that parameters, orders, and
logging can be supported making it flexible and easily extensible. In the terms
of their strengths and weaknesses, one can recognize the fact that different
categories of the design patterns have different strengths. Creational patterns
are outstanding in providing the features of system flexibility and reusability
through the abstraction of the instantiation process. But they may add
confusion when developers must comprehend several creation mechanisms that are
to be used (bin Uzayr, 2022).
Relationships support adaptability of the system and reuse of code since,
although patterns determine relations between objects, they can make the
structure of the code complicated. Behavioral patterns help to enhance system’s
communication and interaction which facilitates its maintainability and
scalability while on the negative aspect it can be tedious since it introduces
a lot of interfaces and interactions in the system. The idea that creational,
structural, and behavioral design patterns each provide a solution to a
specific part of the software design problem is quite fitting (Bhaskaran and Marappan, 2023). Thus, realizing the benefits and
costs of each category, developers will be able to make correct choice
regarding the patterns to apply and, as a result, create more reliable,
adaptable, and easy to maintain software systems.
6.
Conclusion
Senior designers know
creating software is a process in which design patterns play an immensely
valuable role as they provide reliable and tested solutions to typical design
issues. That is why by dividing these patterns into the creational, structural,
and behavioral prototypes, the developers receive a broad set of tools which
can help with the different parts of the software construction, beginning from
the object’s creation and their composition up to their interaction. In
conclusion, design patterns are inevitable in proper development of software,
which brings standard solutions that solve every aspect of software design.
There are creational patterns for flexibility and reuse in object creation,
structural patterns help in efficient composition and organization, and there
are behavioral ones for proper communication and coordination between objects.
In this way, and based on such benefits, the adequate use of these patterns
endows developers with improved assets to build better software solutions for
higher-caliber, more effective and efficient software projects. The
introduction and design patterns’ appreciable utilization are one of the
pillars of efficient and competent software engineering that results into the
creation of software capable of filing the present needs as well as capable of
addressing the future challenges.
7.
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