blob: af64a6e5d51c6abe478f7715c46ab007b834328f [file] [log] [blame]
// This file illustrates the cross language polymorphism using directors.
package main
import (
. "example"
func main() {
// Create an instance of CEO, a class derived from the Go
// proxy of the underlying C++ class. The calls to getName()
// and getPosition() are standard, the call to getTitle() uses
// the director wrappers to call CEO.getPosition().
e := NewCEO("Alice")
fmt.Println(e.GetName(), " is a ", e.GetPosition())
fmt.Println("Just call her \"", e.GetTitle(), "\"")
// Create a new EmployeeList instance. This class does not
// have a C++ director wrapper, but can be used freely with
// other classes that do.
list := NewEmployeeList()
// EmployeeList owns its items, so we must surrender ownership
// of objects we add.
// e.DisownMemory()
// Now we access the first four items in list (three are C++
// objects that EmployeeList's constructor adds, the last is
// our CEO). The virtual methods of all these instances are
// treated the same. For items 0, 1, and 2, all methods
// resolve in C++. For item 3, our CEO, GetTitle calls
// GetPosition which resolves in Go. The call to GetPosition
// is slightly different, however, because of the overridden
// GetPosition() call, since now the object reference has been
// "laundered" by passing through EmployeeList as an
// Employee*. Previously, Go resolved the call immediately in
// CEO, but now Go thinks the object is an instance of class
// Employee. So the call passes through the Employee proxy
// class and on to the C wrappers and C++ director, eventually
// ending up back at the Go CEO implementation of
// getPosition(). The call to GetTitle() for item 3 runs the
// C++ Employee::getTitle() method, which in turn calls
// GetPosition(). This virtual method call passes down
// through the C++ director class to the Go implementation
// in CEO. All this routing takes place transparently.
fmt.Println("(position, title) for items 0-3:")
fmt.Println(" ", list.Get_item(0).GetPosition(), ", \"", list.Get_item(0).GetTitle(), "\"")
fmt.Println(" ", list.Get_item(1).GetPosition(), ", \"", list.Get_item(1).GetTitle(), "\"")
fmt.Println(" ", list.Get_item(2).GetPosition(), ", \"", list.Get_item(2).GetTitle(), "\"")
fmt.Println(" ", list.Get_item(3).GetPosition(), ", \"", list.Get_item(3).GetTitle(), "\"")
// Time to delete the EmployeeList, which will delete all the
// Employee* items it contains. The last item is our CEO,
// which gets destroyed as well and hence there is no need to
// call DeleteCEO.
// All done.
fmt.Println("Go exit")