CODINGSTYLE.md

OSv Coding Style

This is a coding style guide for OSv. It is meant to be helpful, not a tool for bikeshedding patches on the mailing list. The use of common sense when applying these rules is required.

1. Indentation and layout

1.1 We use 4 spaces for indentation, no tabs.

1.2 switch statements, put the case with same indentation as the switch

    switch(op) {
    case 1:
            i++;
            break;
    case 2:
    case 3:
           i *= 2;
           break;
    default:
           break;

1.3 Avoid multiple statements on the same line:

    i++; j++;

1.4 Line length should not exceed 80 characters.

2. Spaces

2.1 Use spaces around binary and ternary operators.

   a = a + 3;
   if (a == 1 || b < 2)
   a += 1;
   a = 1 + 2 * 3;
   a = b < 1 ? b : 1;

2.2 Do not use spaces around unary operators.

   a = -2;
   s = *p;
   for (int i = 3; i < 10; ++i)

2.3 Do not use spaces between a function and its parameters, or a template and its paramters.

   sqrt(2.0)
   std::vector<object*>

2.4 Bind '' or '&' to the type, not the variable ... int a; int& b; ...

Please note that the rule obviously does not make sense when multiple variables are declared on the same line. In such cases, it is preferable to do:

... int *a, *b; ...

3. Braces

3.1 Always use curly braces for if statement, even if it is a one line if.

3.2 When a brace-delimited block is part of a statement (e.g., if, for, switch, WITH_LOCK, etc.), separate the open brace from the statement with a single space - not with a newline.

    if (a == 3) {
        ....
    }

3.2 In inline method, you can use the open braces at the same line of the method.

    int get_age() {
        return age;
    }

3.3 In longer method, the opening brace should be at the beginning of the line.

    void clear()
    {
       .....
    }

4. Naming Convention

4.1 Use all lower snake_case names

5. Commenting

5.1 Use the // C++ comment style for normal comment 5.2 When documenting a namespace, class, method or function using Doxygen, use /** */ comments.

6. Macros, Enums and RTL

6.1 Avoid Macros when a method would do. Prefer enum and constant to macro. 6.2 Prefer "enum class" to "enum".

6.3 Macro names and enum label should be capitalized. For "enum class", non-capitalized values are fine.

7. Functions

7.1 When declaring or defining a function taking no arguments in C++ code, avoid the unnecessary "void" as an argument list.

This "void" was only necessary in C to maintain backward-compatibility with pre-1989 prototype-less declarations, but was never needed in C++ code. For example, write:

void abort() {

and not:

void abort(void) {

7.2 Put no space between function name and the argument list. For example:

double sqrt(double d) {

7.3 Avoid parantheses around return value

"return" is not a function - it doesn't need parantheses. For example:

return 0;
return a + b;