Macros and code sanity

• C macro names MUST be entirely capitalized (see Name capitalization).
• As a general rule, preprocessor macro calls SHOULD NOT break code structure. Further specification of this point is given below.
• Macro call SHOULD NOT appear where function calls wouldn't otherwise be appropriate. Technically speaking, macro calls SHOULD parse as function calls.

  This is bad style: #define MY_CASE(Name) \ case d_ # Name: \ return go_to_ # Name(); [...] switch (direction) { MY_CASE(left) MY_CASE(right) default: break; }

  This is more elegant:

            
  
            #define MY_CASE(Action)    \
              return go_to_ # Action();
            
            [...]
            switch (direction)
            {
               case d_left:
                 MY_CASE(left);
                 break;
               case d_right:
                 MY_CASE(right);
                 break;
               default:
                 break;
            }
            
            

  
  Rationale: macros should not allow for hidden syntactic "effects". The automated standard conformance tool operates over unprocessed input, and has no built-in preprocessor to "understand" macro effects.
• The code inside a macro definition MUST follow the specifications of the standard as a whole.