PHP Traits and Grafts

Reading about traits and grafts in PHP: Request for Comments: Horizontal Reuse for PHP, PHP Traits, Using Traits in PHP 5.4 and PHP Traits: Good or Bad?. They mentioned the Diamond Problem.

I learned some new syntax too! E.g.:

 return $_instance ?: $_instance = new $class;

The ternary operator as a ‘binary’ operator! Cool! See here for details: Since PHP 5.3, it is possible to leave out the middle part of the ternary operator.

Operator overloading in C++

I did my first operator overloading in C++ today. My code ended up being quite different to the example code that I found, but I think I’m happy with it:

class FileData {
  FileData( const string& path );
  static bool LessThan( const FileData& a, const FileData& b );
  bool operator< ( const FileData& );
  unsigned long size() const { return m_size; }
  unsigned long m_size;
  char m_md5[ 16 ];

static bool operator< ( const FileData& a, const FileData& b ) {
  return FileData::LessThan( a, b );

bool FileData::operator< ( const FileData& b ) {
  return FileData::LessThan( *this, b );

bool FileData::LessThan ( const FileData& a, const FileData& b ) {
  unsigned long a_size = a.size();
  unsigned long b_size = b.size();
  if ( a_size == b_size ) {
    return memcmp( a.m_md5, b.m_md5, 16 ) < 0;
  return a_size < b_size;

I'm not sure when it becomes either useful or necessary to define the operator both as a static and as a member function. I did both because I wasn't sure what was required.