Criteria for measuring module independence

Two standards for measuring module independence

There are two qualitative methods to measure the independence of modules: coupling and cohesion. Coupling and cohesion are two qualitative criteria of module independence. When dividing a software system into modules, try to achieve high cohesion and low coupling, improve the independence of modules, and lay the foundation for designing high-quality software structures.

What do the two criteria for measuring module independence mean?

① coupling

Also known as inter-block connection, it refers to a measure of the close relationship between modules in the software system structure. The closer the connection between modules, the stronger the coupling and the worse the independence. The coupling between modules depends on the complexity of the interface between modules, the calling method and the information transmitted.

② Cohesion

Also known as intra-block connection, it refers to the measure of the functional strength of a module, that is, the measure of how closely the elements in the module are combined with each other. If the elements in a module (between statements, between program segments) are more closely related, its cohesion will be higher.

Importance of module independence

Software with independent modules is relatively easy to develop. This is because the functions can be divided and the interface can be simplified, which is especially important when many people develop the same software together.

Independent modules are easier to test and maintain. This is because relatively speaking, the workload required to modify the design and program is relatively small, and the error propagation range is small, so you can "insert" the module when you need to expand the function. In a word, module independence is the key to excellent design, and design is the key link to determine software quality.