Hi, I have been investigating move semantics and think that I came up with a solution that is strongly influenced by both David Abrahams' move approach and Andrei Alexandrescu's mojo, but solves some of the problems I have encountered with them. The basic idea is to use the explicit keyword to force the compiler to use the X(X const &) constructor only in two cases. 1) When explicitly copying a const object i.e. X const x; X y(x); //use explicit copy constructor 2) When passing by const ref void f(X const &); X makeX(); void foo() { f(makeX()); //use explicit copy constructor } In all other cases the other constructor take precedence. Note that the template trick David Abrahams uses in his move approach would lead to an error on a conforming compiler when confronted with case #2 (unless more recent versions corrected this). I chose to keep the temporary and constant subtypes from mojo because they allow me to discriminate between const values, non-const rvalues and non-const rvalues. The lack of this capability was the major problem I had with David Abrahams' move. My use-case was a vector-like container that increases but never decreases the size of its backing store. In order to provide the never decreasing backing-store semantic, operator = moves the backing store from a temporary only if the new data does not fit in the existing space. Hence, operator = must be able to discriminate between temporaries and non-temporaries. My solution fullfills almost all the requirements I had: 1) passing by value moves non-const rvalues and copies everithing else. 2) its is transparent to the user of the class. Alexandrescu's Mojo fails this because of the special return type, while Abrahams' move fails it because of the pass-by-const-ref problem described above. 3) it allows to discriminate between constants, non-const lvalues, and non-const rvalues. Alexandrescu's Mojo allows it, while Abrahams' move does not. 4) Provides move semantics to templated classes with (almost) no odd side-effect. The only side-effect is that template type deduction does not work with temporary discrimination. Hence in the sample code the template type of the "discriminate" function must be specified explicitly. please find attached a sample file illustrating my move approach. I tested the code with gcc 3.3.1 and successfully compiled it with comeau online. What do you think? 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