Re: [Boost-users] Using boost function with virtual methods

On 7/2/11 1:25 PM, Igor R wrote:

...

The inheritance is going the wrong way. An actionFuntion instance might be called with any RegressionTestScenario*. But you can't call a CurveGenRegressionTestScenario method with any old RegressionTestScenario* -- only a RegressionTestScenario* that is also a CurveGenRegressionTestScenario* would be valid. The compiler isn't going to synthesize logic for you to dynamic_cast(*your_first_param) (which throws unless your_first_param is in fact a CurveGenRegressionTestScenario*). If you want such logic, you'll have to code an adapter and store that. It has nothing to do with inheritance. The following code won't compile as well:

struct A { void f(int i); };

boost::function func = &A::f;

Note that func = $A::f does not have the same signature a &g where g is defined as void g(A*, int); It may act in an analogous manner, but the language does not make them the same. I have seen some systems were the calling convention even put the A* in a different register for the two calls. -- Richard Damon