Introduction

C++11’s most pervasive feature is probably move semantics, and the foundation of it is distinguishing expression that are rvalues from those that are lvalues.

• To show how confusing rvalue vs lvalue could be, a parameter of rvalue reference type is itself an lvalue

// bar is an lvalue,
// though it has an rvalue reference type.
void foo(Bar&& bar);

• C++11 makes distinction between parameter and argument
  • (See perfect forwarding)
  • Function’s parameter is an lvalue
  • Argument passing to a function could be either rvalue or lvalue

// Parameter is an lvalue
void foo(Bar bar);

// bar is a copy-constructed copy of x
foo(x);

// bar is a move-constructed copy of x
foo(std::move(x));

• Perfect forwarding is to preserve the original argument’s rvalueness or lvalueness
• Regrettable, no terminology yet that distinguishes between copy-constructed copy and move-constructed copy
• (vs declaration) Definition provides the storage locations or implementation details
• Meyers defines a function’s signature = return type + parameter types
  • noexcept or constexpr are excluded from signature
  • C++ standard’s definition is slightly different
• Prefer nullptr over 0 or NULL
• Prefer alias declaration over typedefs