BOINC coding style

All languages

Code factoring

• If code is repeated, factor it out and make it into a function.
• If a function becomes longer than 100 lines or so, split it up.
• If a file is becoming 'landfill', split it up.
• C++ .h files often contain both interface and implementation. Clearly divide these.

Code documentation

• .cpp files have a comment at the top saying what's in the file (and perhaps what isn't).
• Functions are preceded by a comment saying what they do.
• structs and classes are preceded by a comment saying what they are.

Naming

• Names should be descriptive without being verbose (local variables names may be short).
• Class and type names, and #defined symbols, are all upper case, with underscores to separate words.
• Variable and function names are all lower case, with underscores to separate words.
• No mixed case names.

Indentation

• Each level of indentation is 4 spaces (not a tab).
• Multi-line function call:

  func(
      blah, blah, blah, blah, blah,
      blah, blah, blah, blah, blah
  );
  

• switch statements: case labels are at same indent level as switch:

  switch (foo) {
  case 1:
      ...
      break;
  case 2:
      ...
      break;
  }
  

Constants

• There should be few numeric constants in code. Generally they should be #defines.

Braces

• Opening curly brace goes at end of line (not next line):

  if (foobar) {
      ...
  } else if (blah) {
      ...
  } else {
      ...
  }
  

• Always use curly braces on multi-line if statements.

  if (foo)
      return blah;     // WRONG
  

• 1-line if() statements are OK:

  if (foo) return blah;
  

Comments and #ifdefs

• Use /// for all comments. The documentation is generated using Doxygen, so you should have a look at this example:

/// Brief description for class test.

/// A more elaborate description for class test,
/// could be more than one line.
class Test
{
  public:

    /// A constructor.
      
    /// A more elaborate description of the constructor.
    Test();

    /// A destructor.
    /// A more elaborate description of the destructor.
    ~Test();
    
    /// a normal member taking two arguments and returning an integer value.
    /// @param a an integer argument.
    /// @param s a constant character pointer.
    /// @see Test()
    /// @see ~Test()
    /// @see testMeToo()
    /// @see publicVar()
    /// @return The test results
    int testMe(int a,const char *s);
       
    /// A pure virtual member.
    /// @see testMe()
    /// @param c1 the first argument.
    /// @param c2 the second argument.
    virtual void testMeToo(char c1,char c2) = 0;
   
    /// a public variable.

    /// Details.
    int publicVar;
       
    /// a function variable.

    /// Details.
    int (*handler)(int a,int b);
};

• Comment out blocks of code as follows:

  #if 0
      ...
  #endif
  

C++ specific

Includes

• A .cpp file should have the minimum set of #includes to get that particular file to compile (e.g. the includes needed by foo.cpp should be in foo.cpp, not foo.h).
• foo.cpp should include foo.h first; after that, includes should be ordered from general (<stdio.h>) to specific (thisfile.h).

Extern declarations

• foo.h should have 'extern' declarations for all public functions and variables in foo.cpp There should be no 'extern' statements in .cpp files.

Use of static

• If a function or variable is used in only one file, declare it static.

Things to avoid unless there's a truly compelling reason:

• Operator or function overloading.
• Templates.

Things to avoid

• Use typedef (not #define) to define types.
• Don't use memset() or memcpy() to initialize or copy classes that are non-C compatible. Write a default constructor and a copy constructor instead.

Error codes

• (Almost) all functions should return an integer error code. Nonzero means error. See lib/error_numbers.h for a list of error codes.
• Calls to functions that return an error code should check the code. Generally they should return non-zero on error, e.g.:

  retval = blah();
  if (retval) return retval;
  

Structure definitions

struct FOO {
    ...
};

You can then declare variables as:

FOO x;

PHP specific

HTML

PHP scripts should output "HTML 4.01 Transitional". The HTML should pass the ​W3C validator. This means, e.g., you must have quotes around attributes that have non-alpha characters in them. However, all-alpha attributes need not have quotes, and tags like <br> and <p> need not be closed.

The HTML need not be XHTML.

This means no self-closing tags like <br />.

Getting POST and GET data

Do not access $_POST or $_GET directly. Use get_int(), get_str(), post_int() and post_str() (from util.inc) to get POST and GET data. These undo the effects of PHP magic quotes.

Database access

• Use the database abstraction layer.
• If a POST or GET value will be used in a database query, use BoincDb::escape_string to escape it.