[Corelinux-develop] Changes to MetaType

[Frank V. C. <fr...@co...>]

Recent check-in includes the ability to declare a function dispatch
table, each member of the table containing a text descriptor and
function address that can be used to direct the appropriate object
method call.

For example (lots of stuff omitted) :

// in A.hpp

class A : public virtual FrameworkEntity
{
	DECLARE_METATYPEMEMBERS( A );
public:
        int	doSomething( int v );
};

// in A.cpp

// Either use macros or create by hand, to define the function
// If using the macro, then just provide the body 
// **note the names

DISPATCH_FUNCTION( A, doSomething )
    *((int *)ret) = myPointer->doSomething( (int) args[0] );
CLOSE_DISPATCH_FUNCTION;

// Which expands to

static extern "C" void AdoSomething
    (
	FrameworkEntityPtr aClass,
	void		   **args,
	void		   *ret
    )
{
    A *myPointer = A::castdown( aClass );
    *((int *)ret) = myPointer->doSomething( (int) args[0] );
}

// Then create a dispatch descriptor

DEFINE_DISPATCH_DESCRIPTOR( A, doSomething, doSomething );

// where first arg is class
//       second arg is stringified for lookup
//	 third arg is the method
// 

// Create the table to collect all descriptors

OPEN_DISPATCH_TABLE( A )
    DEFINE_DISPATCH_ENTRY( A, doSomething )
CLOSE_DISPATCH_TABLE;

DEFINE_METATYPE( A, someid, someversion );

// In user application, the ability will be used to call the method with
// the context of the instance (anA)

int main( void )
{
    A	anA;
    int	x(5);
    int	y(0);

    anA.getType()->dispatch(&anA,"doSomething",(void **)&x,(void *)&y);
}

The MetaType method (dispatch) should be in sometime tonight, all the
macros are in.

-- 
Frank V. Castellucci
http://corelinux.sourceforge.net
OOA/OOD/C++ Standards and Guidelines for Linux
http://PythPat.sourceforge.net
Pythons Pattern Package