Software design principles focus on empowering you to handle the complexity of the design process in a more effective and efficient manner. These principles help you reduce the effort required for designing software systems and even lower the chances of you introducing errors during the design process.
We’ve broken down 19 of the most important software design principles into 3 categories here.
Basic software design principles
Pretty much every modern software technology vastly involves working with abstractions of different types. This general approach is known as object-oriented software development.
Making use of abstractions involves hiding the coding complexities and redundant details behind high-level abstractions and not getting into them till the pont when you absolutely need to do that.
Because of abstraction-based design concepts it is possible for to reduce the amount of irrelevant data, accelerate your development process, and in general, improve the quality of your programming outcomes.
Refinement involves eliminating structural impurities by moving from higher levels of software design (abstractions) to lower levels in a sequential manner.
The idea is that refinement is an incremental process in which a team of software engineers will drill down to get more technical details at every increment. In this way, software design is consistently improved and expanded without wasting time on irrelevant or periphary issues.
Modularity refers to the division of software into separate modules, each of which are named and addressed differently and then get integrated later to get a completely functional software. This is the only property that makes it possible for a program to be intellectually manageable. Single large programs tend to be rather hard to understand and read because of the huge quantity of reference variables, control paths, global variables, etc.
Modularity makes it possible for large programs to be written by multiple
If the problem is small, you can tackle the entire problem at one time. But for a larger problem, you should follow the divide and conquer approach. Slice the problem into smaller pieces that can be handled easily on their own.
These pieces can’t be completely independent of each other due to the fact that they need to come together to form the system. They need to communicate and co-operate with each other in order to solve the problem.
The advantages of problem partitioning are that the software becomes easier to test, modify, maintain, and expand.
It is critical for data to be protected from unauthorized access. For that reason, secure software development life-cycle principles need to be applied and propagated throughout the entire software structure.
Refactoring is all about bringing improvements to internal software structure without having any effect on its behavior or functions. Refactoring is an integral part of the perpetual software maintenance process and it involves frequently reviewing and improving the code to make it lighter and more powerful.
While this principle isn’t limited to software design, it is still very important in this field. You should avoid complexity and write code that is easy to implement and maintain.
SOLID software design principles
The SOLID principles are the 5 basic object-oriented programming principles used in Agile software development.
A class should have only one job, and only one reason to change. If a class has multiple responsibilities, it could weaken the design and cause damages when changes occur.
The SRP principle helps avoid coupling of responsibilities and thus improves the design’s cohesion as a whole.
According to this software design principle, after a class of code has been created and tested, you should keep it closed to modification, but open to extension. Over the course of the development process, your requirements might change and new functionalities might be requested. If you modify your code, you might add errors into your existing code.
The open/closed principle keeps your class code fundamentally intact, but enables you to extend it to include new functionalities.
This software design principle suggests that objects of a superclass should be replaceable with objects of its subclasses, which means that they should behave in the same way. As an example, if Y is a subclass of X, objects of Y should be able to replace objects of X without having a negative impact on the performance of the program. Basically, objects of a subclass can replace objects of the superclass without undermining the system.
Every class must have an isolated interface of its own and class dependencies must be based on the smallest possible interface. A large and complex interface which has multiple class dependencies would add methods to the interface that the clients don’t require.
According to this principle, high-level modules should not be dependent on low-level modules, and both should depend on abstractions. Also, abstractions should not depend on details, but it should be the other way around. Abstract interfaces and abstract classes happen to be more stable than details which are variables. Architectures built on abstractions have greater stability than those built on details.
Modern software design principles
You want to make sure that you avoid focusing on a very narrow perspective without considering side effects and other factors. You need to evaluate all possible options and make sure that your performance is in alignment with the most rational scenarios.
Don’t spend your time bother to build solutions that already exist and are available. All modern programming takes place in the object-oriented model and you can easily find free libraries, ready-made modules, and API-based solutions that can accelerate your project.
Your software system design should be available for traceability analysis. You need to track changes to the product and maintain high-quality documentation with all product components being represented through integral interrelationships with their predecessors and successors.
Graceful degradation means that even if there is an error or an incident while the program is being executed, the software should continue running smoothly instead of just shutting down. If it just shut down, your users could lose their data or changes which they made - and that’s something you can’t have happening.
You should assess and evaluate your design for quality. The quality of your design needs to be focused on during assessments and evaluations.
Your software should be able to adjust to the changes that might be required according to your users’ needs.
You should check your design and have it reviewed to see whether there are any errors and if there is anything that you could do to eliminate or minimize those errors in your design.