Software Design Patterns Every Dev Have To Know

Stfalcon.com
11 min readSep 1, 2023

Crafting sophisticated, resilient, and efficient software applications is consistently challenging due to the myriad of challenges inherent in the realm of software development. The process of application creation often entails developers encountering a multitude of obstacles that necessitate resolution. This scenario is commonly referred to as a “Problem in a Context.” The remedy invariably lies in the application of a Design Pattern.

Software design patterns encompass reusable resolutions for recurring challenges within specific contexts in software design. They do not constitute finalized designs that can be directly transcribed into code; rather, they serve as templates for addressing common problems that developers can employ across diverse situations.

What does a Software Design Pattern mean?

Design patterns represent general solutions to commonly faced challenges in software design. They take the form of pre-designed templates that can be adapted to tackle recurring design problems within your code.

Software design patterns for web development suggest models & techniques for developing and solving recurrent software problems and tasks. By incorporating well-established patterns, software engineers can generate code that is extensible, adaptable, and of superior quality, showcasing their expertise in the field.

Patterns are often mistaken for algorithms ’cause both ideas describe decisions to certain issues. A programming design pattern is a higher-level description of a decision than an algorithm that always specifies a distinct set of steps that lead to a specific result. The code may vary even when utilizing the same pattern with two different programs.

Format of a Software Design Pattern

Contemporary design patterns are often outlined in a comprehensive manner, allowing developers to apply them across various scenarios. The components constituting a pattern description usually include the following sections:

  • Motivation further explains the problem & how the pattern can resolve it.
  • The intent of the pattern describes both the problem and the decision.
  • The class structure delineates each constituent of the pattern and elucidates their interconnections.
  • The code illustration in a widely-used programming language simplifies the comprehension of the underlying concept of the pattern.

Certain compilations of design patterns offer supplementary valuable insights, encompassing details such as the pattern’s relevance, stages of implementation, and associations with other patterns.

Types of Design Patterns

Software design patterns differ in their intricacy, level of elaboration, and extent of relevance across the entire system. To facilitate comprehension, this can be likened to road construction: just as you can enhance the safety of a crosswalk by introducing traffic lights or constructing a multi-level interchange with pedestrian tunnels.

Architectural patterns are the most universal and high-level ones. Devs can utilize these patterns in almost any language. In contrast to other patterns, they can be utilized to create the architecture of the entire app.

All patterns can also be classified according to their goal. Three primary design patterns types are:

  • Structural patterns elucidate methods for organizing classes within intricate structures while upholding efficiency and adaptability.
  • Creational patterns include object creation methods that improve flexibility and current code reuse.
  • Concurrency design patterns are utilized in multi-threaded programming to facilitate effective software design and development.
  • Behavioral patterns ensure quick communication & the allocation of functions between objects.

Design Patterns Advantages

The software design pattern has the potential to expedite the development process, presenting proven development paradigms that save time by obviating the necessity to devise new patterns whenever a problem emerges. There are two primary benefits to employing design patterns.

First, they provide a method for resolving software development-related challenges through a well-established approach. This solution simplifies the creation of highly cohesive modules with minimal coupling. Additionally, they segregate potential variations in system requirements, thereby enhancing the comprehensibility and maintainability of the entire system.

Second, Second, design patterns improve the effectiveness of designer-to-designer communication. When discussing system design, software professionals can refer to the pattern used to solve a specific issue and instantly visualize the high-level design in their minds.Best Software Design Patterns

While a total of 26 software design patterns have been identified thus far, with 23 originating from the “Gang of Four,” only a handful are recognized as the most pivotal and impactful. This segment outlines the top 7 software design patterns, delving into their importance and suitable utilization.

Singleton Pattern

The Singleton represents a creational software design pattern that confines the instantiation of a class to a sole instance. This class possesses just one instance, offering a universal entryway to this particular instance.

It’s one of the known “Gang of Four” programming patterns, which explain how to refer recurrent problems in object-oriented software. The pattern is helpful when only one object is required to coordinate performances throughout a system.

An analogy from real life

The Singleton pattern can be illustrated through the analogy of a government. In every country, there exists a single legitimate government. The phrase “the Government of A” serves as a universal entryway denoting a group of individuals in authority.

When to employ?

  • Utilize the Singleton design+pattern when a class should only have a single instance that is accessible to all customers; an example would be a single database object that is shared by various program components.
  • Utilize the Singleton pattern if you need more precise control over global variables.

Pros:

  • You get a global access point to that instance
  • A class has a single instance
  • Only first-time requests initialize the singleton object.

Cons:

  • The Singleton programming pattern may hide a poor design. For instance, when the program’s components know too much about one another.
  • The Single Responsibility Principle is broken. The pattern simultaneously resolves two issues.

Factory Method

The Factory Method, also referred to as the Virtual Constructor, empowers the generation of objects within a superclass, granting subclasses the ability to alter the kind of objects created.

Additional classes can be incorporated into the factory when necessary. Initially, this alteration might appear inconsequential, merely transferring the constructor call from one program segment to another. However, it’s crucial to recognize that by doing this, you gain the ability to modify the product class that the factory method generates through subclass overrides.

Use the factory method

  • when you want to give users of your library or framework a way to modify its internal components;
  • when you want to conserve system resources by reusing existing objects rather than rebuilding them each time;
  • when you’re still determining what kinds and dependencies the objects your code will need to work with are.

Pros

  • Open/Closed Principle. The program can add new product types without altering the client code.
  • Single Responsibility Principle. The product creation code can be moved to one spot in the program, making it simpler to maintain.
  • There is no hard link between the creator and the product.

Cons:

  • Introducing numerous new subclasses to implement the software design pattern could potentially introduce complexity into the code. The optimal scenario arises when you integrate the pattern into an existing hierarchy of creator classes.

Facade

The Facade represents a structural program design pattern that furnishes a simplified interface for intricate collections of classes, akin to a library, framework, or any other subsystem characterized by numerous interconnected components.

It could be the perfect decision when you need to integrate your application with a complex library with dozens of features but you demand a tiny portion of its functionality.

The facade programming design pattern holds notable efficacy in personalized marketing strategies, as it adapts to a user’s location or actions to offer each individual a distinct and customized experience.

Analogy from real life

When a store client orders over the phone, the assist desk operator is a front for all department & store services. It ensures the consumer with a simple voice interface to payment gateways, an ordering system, and delivery services.

Employ the Facade pattern

  • When you want to layer a subsystem’s structure.
  • when you need a simple yet constrained interface to a complex subsystem.

Pros

  • You can separate your code from a subsystem’s complexity.

Cons

  • Facades have the potential to transform into god objects connected to every application class.

Strategy

Sometimes termed a policy pattern, the strategy design pattern empowers you to establish a collection of algorithms, isolate each algorithm within a distinct class, and establish interchangeability among the objects of these classes. For instance, a cluster of algorithms could be applied to “sort” products on an eCommerce website, factoring in attributes such as size, color, price, and more. The strategy is executed based on the customer’s interactions.

The strategy design+pattern is a straightforward design pattern for personalization marketing strategies. To ensure each consumer with a unique experience, the strategy design pattern responds to a customer inputs, location, or actions.

Analogy from real life

Consider the scenario of traveling to the airport. You have options like riding your bicycle, booking a taxi, or taking a bus. These represent your modes of transportation. Your choice of strategy can be determined by factors such as your budget and time limitations.

Utilize the Strategy pattern

  • when you need to utilize a variety of algorithm variants within an object & be able to switch between them while the object is being utilized.
  • To segregate the implementation specifics of an algorithm from its business logic, which might be of lesser importance.
  • When a significant quantity of closely interconnected classes differ primarily in their execution of a specific behavior.

Pros

  • You can separate an algorithm’s implementation specifics from the code that employs it.
  • You can use composition in place of inheritance.
  • At runtime, you can change the algorithms used inside an object.

Cons

  • To choose the best strategy, clients must be aware of the variations among them.
  • There is no need to add new classes and interfaces to the program associated with the pattern if you only have a few algorithms and they only change a little.

Observer

The observer represents a behavioral software design pattern that permits the establishment of a subscription mechanism, alerting numerous objects to events that impact the object they are observing.

The observer programming pattern institutes a one-to-many correlation between an object (the subject) and its dependents (the observers). Whenever an observer undergoes a change, the subject is notified.

Any event-driven programming, such as notifying a consumer of a new comment on Facebook or sending an email when item ships, can benefit from utilizing the observer design pattern.

Analogy from real life

If you subscribe to a newspaper or magazine, you can avoid going to the store to see if the upcoming problem is available. Instead, the publisher delivers fresh problems straight to your mailbox.

A roster of subscribers is maintained, with the publisher being aware of their magazine preferences. If subscribers decide they no longer wish to receive new magazine issues, they have the option to remove their names from the list at any point.

Apply the Observer pattern

  • when specific situations or for a brief period, some objects in your app need to observe others.
  • when the set of objects is dynamically changing or unknown in advance, and changing the state of one object may require changing the states of other objects.

Pros

  • At runtime, you can build relationships between objects.
  • Open/Closed Principle. You can add new subscriber classes without requiring changes to the publisher’s code if there is a publisher interface.

Cons

  • Subscribers are notified in an unpredictable sequence.

Builder

The Builder is a creational design pattern that facilitates the gradual construction of intricate objects. Employing identical construction code, this pattern permits the generation of diverse types and representations of objects.

In the builder pattern, only the necessary steps for each object iteration are invoked as it is constructed through a series of sequential steps.

The pattern breaks down the object creation process into multiple steps (buildWalls, buildDoor, etc.). Importantly, not all of these steps need to be invoked; only the processes required to construct a particular configuration of the object are called.

Utilize the Builder pattern

  • when you require your code to have the capability of generating diverse renditions of a particular product.
  • to eliminate a “telescoping constructor.”
  • to construct intricate objects, like composite trees, for instance.

Pros

  • You can apply the same construction code to a variety of product representations.
  • You have three options for building objects: sequentially, asynchronously, or recursively.
  • Single Responsibility Principle. You can separate the product’s business logic from complex construction code.

Cons

  • As the pattern mandates the formation of multiple new classes, it leads to an overall increase in the code’s complexity.

Adapter

The Adapter is a structural design pattern that facilitates collaboration between objects possessing disparate interfaces.

An adapter envelops one of the objects to obscure the complex conversion taking place behind the scenes. The object being wrapped remains unaware that it is enclosed within an adapting layer. For instance, you could enclose a device utilizing meters and kilometers within an adapter that transforms all the data into imperial units like feet and miles.

Analogy from real life

A novel encounter might await you when trying to charge your laptop during your inaugural visit to Europe from the US. Diverse countries adhere to distinct norms for power plugs and sockets. The German socket won’t accommodate your US plug due to this divergence. The solution to this predicament lies in a power plug adapter, equipped with both an American-style socket and a European-style plug.

Use the Adapter pattern

  • when you use an existing class whose interface conflicts with your code.
  • when creating a middle-layer class that acts as a translator between the code and a legacy class, a third-party class, or any other class with an incompatible interface.
  • when you want to reuse many already-existing subclasses that don’t share a common feature and are ineligible for inclusion in the superclass.

Adapter Pattern Pros

Single Responsibility Principle: By segregating the interface or data conversion code from the primary business logic of the program, you uphold this principle. Open/Closed Principle: You can introduce new adapter types to the program without inducing malfunctions in the existing client code, adhering to this principle.

Adapter Pattern Cons

Introducing a multitude of new classes and interfaces leads to an elevation in the overall complexity of the code. Occasionally, it proves simpler to modify the service class to align with the rest of the codebase.

Architectural Patterns vs. Design Patterns

Architecture patterns determine the physical placements of components, establish their interconnections, and ultimately designate the tools for constructing these components.

Software architecture design patterns should provide thorough insights into the implementation of specific components, while architecture patterns concentrate on the broader perspective. Component design employs classes, interfaces, abstract classes, and other object-oriented features to accomplish the designated tasks for each component.

The software systems are constructed according to architectural patterns. Design patterns solve recurring problems in software design.

Architecture Patterns vs. Design Patterns:

  • A design pattern embodies the practical realization, while an architectural pattern resembles a blueprint.
  • Architecture functions as the foundational framework upon which all other elements are constructed, while design patterns structure classes to tackle prevalent challenges.
  • Architecture comes in the designing phase, and design patterns come in the building phase.

To Sum Up

Possessing a seasoned team is essential for understanding when to employ software design patterns, and equally crucial is recognizing when not to use them, along with proficiently executing each pattern.

Stfalcon is a leading software development company with 13 years of experience. We prioritize establishing enduring relationships with our customers & building software your company will enjoy utilizing.

If you’re searching a dedicated software development team who will dress your idea in code, hit us up to get a free consultation from our specialists.

Originally published at https://stfalcon.com.

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Stfalcon.com

IT company designing custom web services and mobile apps. Our goal is to create useful and convenient software. We are the founder of the Air Alert app