[C/C++] - C++ optimizations for initialization

1 - Use Initialization Lists

Always use initialization lists in constructors. For example, use

TMyClass::TMyClass(const TData &data) : m_Data(data)

{

}

rather than

TMyClass::TMyClass(const TData &data)

{

m_Data = data;

}

Without initialization lists, the variable's default constructor is invoked behind-the-scenes prior to the class's constructor, then its assignment operator is invoked. With initialization lists, only the copy constructor is invoked.

2 - Initialize on Declaration

Whereever possible, initialize variables at the time they're declared. For example,

TMyClass myClass = data;

is faster than

TMyClass myClass;

myClass = data;

Declaration then initialization invokes the object's default constructor then its assignment operator. Initializing in the declaration invokes only its copy constructor.

3 - Delay Variable Declarations

Leave variable declarations right until the point when they're needed. Remember that when a variable is declared its constructor is called. This is wasteful if the variable is not used in the current scope.