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I want to wrap some existing C code with C++. The function I want to call back is declareed like this: struct X {     double foo(double x , void * p); };

Idealy I would like to use lambda to remove the void* and replace it with _1, _2 etc. But I am not sure how > that works with callbacks.

Use boost::bind or boost::lambda::bind. For example: // An instance of x X x; // A binary function boost::function fBinary; // A unary function boost::function fUnary; // A nullary function boost::function fNullary; // Bind x.foo to binary function fBinary = boost::bind(&X::foo, boost::ref(x), _1, _2); // Bind x.foo to unary function "hardcoding" second parameter fUnary = boost::bind(&X::foo, boost::ref(x), 5.25, _1); // Bind x.foo to nullary function "hardcoding" first and second parameter int i = 5; fNullary = boost::bind(&X::foo, boost::ref(x), 5.25, &i); // Execute binary function passing both arguments fBinary(5.25, &i); // Execute unary function passing 1 argument fUnary(&i); // Execute nullary function fNullary(); Hope this helps, -delfin