1, high cohesion: cohesion is a measure of the degree of correlation between components in a module. A highly cohesive module is closely related internally, just like an inseparable whole. If the function of this module is relatively simple, the difficulty of module implementation and maintenance will be greatly reduced.
2. Low coupling: It should be noted that coupling is a measure of the degree of dependence between modules. Low coupling means better independence between modules, and changing one module will not affect other modules. Cohesion and coupling are closely related. Strong coupling of a module with other modules usually means weak cohesion, and strong cohesion of a module usually means weak coupling with other modules.
3. Information hiding: Information hiding means that the module only discloses what must be known to the outside world and hides all other contents. In the interface design of module design, the principle of information hiding is fully embodied. Interfaces are external features of modules and should be open. Data structure, algorithm and implementation are the internal characteristics of the module and should be hidden. A module only provides a limited interface, which is the only way for the module to interact with the outside world.
Information hiding comes down in one continuous line with the two principles of high cohesion and low coupling. Both reflect the design idea of module independence. In addition, information hiding also contains profound China culture-beauty on the outside and wisdom on the inside. The interface design of the module pursues simplicity, high efficiency, small and beautiful, which is "showing off"; Data structure and algorithm, these complex designs are concentrated in the module, which is the "clock meeting". Only by following these design principles can we make a good module design.
Refer to the above? Baidu Encyclopedia-Information System Design