Big talk design mode note single duty principle open-closed principle

Single responsibility principle (SRP), in the case of a class, there should be only one cause for its change.

Personally think that this principle is too idealistic, only one is not absolute, reasonable is good.

Much of what software is designed to do is to discover responsibilities and separate those responsibilities from "ASD"

If you can think of more than one motive to change a class, then this class has more than one responsibility.

MVC, it can be said that the principle of good use, but sometimes some small projects can be directly executed in the service SQL statement, is also possible.

The open-close principle is that software entities (classes, modules, functions, and so on) should be expandable, but not modifiable.

For the expansion is open (open for extension), the change is closed (Closed for modification).

But no matter how "closed" the module is, there will be some changes that cannot be closed to it, since it is not possible to completely close, the designer must choose the module that he designed should be closed to that change. He must first guess what kinds of changes are most likely to occur and then construct abstractions to isolate those changes.

Big talk design mode note single duty principle open-closed principle