Coincidental cohesion is one of the levels of cohesion in software engineering, and it represents the lowest and least desirable form of cohesion within a module or component. Cohesion refers to the degree to which the elements within a module are related to each other. In the case of coincidental cohesion, the elements within a module have no meaningful or logical relationship to each other; they are grouped together merely by coincidence or historical reasons.
Here are the key characteristics and considerations related to coincidental cohesion:
Lack of Logical Relationship: In modules with coincidental cohesion, the elements or functions are unrelated in terms of their functionality or purpose. They do not work together to achieve a specific goal or function.
Absence of Common Theme: There is no common theme, purpose, or shared functionality that justifies grouping these elements together. They are typically unrelated and may perform completely different tasks.
Maintenance Challenges: Modules with coincidental cohesion are often challenging to maintain. Changes to one element may unintentionally affect other unrelated elements within the module.
Readability and Understandability: Code within modules with coincidental cohesion can be difficult to read, understand, and maintain. This can lead to decreased developer productivity and increased likelihood of introducing errors.
Testing Difficulty: Testing modules with coincidental cohesion can be complex because there is no clear functional boundary or logic to guide the testing process. It may be unclear how different elements interact or whether they need to be tested together.
Refactoring Opportunity: In many cases, modules with coincidental cohesion may be candidates for refactoring. Elements can be reorganized into more logically cohesive modules to improve code quality.
Examples: Examples of modules with coincidental cohesion might include a module that contains a mix of unrelated utility functions, a class with methods that handle different and unrelated concerns, or a module that has accumulated code over time without a clear structure.
Best Practices: Coincidental cohesion is generally undesirable in software engineering. Developers strive to design modules with higher levels of cohesion, such as functional cohesion, where elements are grouped based on a common function or purpose.
Modularity: A fundamental principle in software engineering is promoting modularity, which coincidental cohesion undermines. Well-structured and modular code is easier to develop, test, and maintain.
In summary, coincidental cohesion represents the lowest level of cohesion in software engineering, where elements within a module have no meaningful or logical relationship to each other. Developers aim to avoid coincidental cohesion and instead design modules with higher levels of cohesion to improve code quality, maintainability, and readability. Refactoring coincidentally cohesive modules is a common practice to enhance software quality and structure.
