The art of Engineering (1): try to package things that do not need to be exposed

#ifndef _TEST_H_
#define _TEST_H_

#define SUCCESS 1
/**
*	do Something
*/
#endif // _TEST_H_

This is a very common header file , We define a macro in it . According to past experience , Defining macros in header files is a common operation , But in fact, there is a security risk here .
Here we give a principle , namely ：
For things that don't need to be known to the outside world , Should find ways to hide it
The reason is the same as the encapsulation in the object-oriented idea , Expose the interface to the outside world , The outside world may make unnecessary modifications . Besides , There may also be conflicts with macros defined by others .
The solutions are as follows ：

1. Define the macro here in the implementation file
2. stay cpp The magic number is defined in the file by using the global namespace with constants
3. Use enumeration to define magic numbers