Memory management fixes and comment corrections

git-svn-id: https://swig.svn.sourceforge.net/svnroot/swig/trunk@5656 626c5289-ae23-0410-ae9c-e8d60b6d4f22
This commit is contained in:
William S Fulton 2004-01-20 21:28:29 +00:00
commit 01a1e83dcb

View file

@ -10,6 +10,10 @@ class CEO extends Manager {
public String getPosition() { public String getPosition() {
return "CEO"; return "CEO";
} }
// Public method to stop the SWIG proxy base class from thinking it owns the underlying C++ memory.
public void disownMemory() {
swigCMemOwn = false;
}
} }
@ -26,9 +30,9 @@ public class main {
public static void main(String argv[]) public static void main(String argv[])
{ {
// Create an instance of our employee extension class, CEO. The calls to // Create an instance of CEO, a class derived from the Java proxy of the
// getName() and getPosition() are standard, the call to getTitle() uses // underlying C++ class. The calls to getName() and getPosition() are standard,
// the director wrappers to call CEO.getPosition. e = CEO("Alice") // the call to getTitle() uses the director wrappers to call CEO.getPosition().
CEO e = new CEO("Alice"); CEO e = new CEO("Alice");
System.out.println( e.getName() + " is a " + e.getPosition() ); System.out.println( e.getName() + " is a " + e.getPosition() );
@ -41,29 +45,23 @@ public class main {
EmployeeList list = new EmployeeList(); EmployeeList list = new EmployeeList();
// EmployeeList owns its items, so we must surrender ownership of objects // EmployeeList owns its items, so we must surrender ownership of objects we add.
// we add. This involves first calling the __disown__ method to tell the e.disownMemory();
// C++ director to start reference counting. We reassign the resulting
// weakref.proxy to e so that no hard references remain. This can also be
// done when the object is constructed, as in: e =
// CEO("Alice").__disown__()
// e = e.__disown__();
list.addEmployee(e); list.addEmployee(e);
System.out.println( "----------------------" ); System.out.println( "----------------------" );
// Now we access the first four items in list (three are C++ objects that // 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 // 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 // methods of all these instances are treated the same. For items 0, 1, and
// 2, both all methods resolve in C++. For item 3, our CEO, getTitle calls // 2, all methods resolve in C++. For item 3, our CEO, getTitle calls
// getPosition which resolves in Java. The call to getPosition is // getPosition which resolves in Java. The call to getPosition is
// slightly different, however, from the e.getPosition() call above, since // slightly different, however, because of the overidden getPosition() call, since
// now the object reference has been "laundered" by passing through // now the object reference has been "laundered" by passing through
// EmployeeList as an Employee*. Previously, Java resolved the call // EmployeeList as an Employee*. Previously, Java resolved the call
// immediately in CEO, but now Java thinks the object is an instance of // immediately in CEO, but now Java thinks the object is an instance of
// class Employee (actually EmployeePtr). So the call passes through the // class Employee. So the call passes through the
// Employee proxy class and on to the C wrappers and C++ director, // Employee proxy class and on to the C wrappers and C++ director,
// eventually ending up back at the CEO implementation of getPosition(). // eventually ending up back at the Java CEO implementation of getPosition().
// The call to getTitle() for item 3 runs the C++ Employee::getTitle() // The call to getTitle() for item 3 runs the C++ Employee::getTitle()
// method, which in turn calls getPosition(). This virtual method call // method, which in turn calls getPosition(). This virtual method call
// passes down through the C++ director class to the Java implementation // passes down through the C++ director class to the Java implementation
@ -78,12 +76,7 @@ public class main {
System.out.println( "----------------------" ); System.out.println( "----------------------" );
// Time to delete the EmployeeList, which will delete all the Employee* // Time to delete the EmployeeList, which will delete all the Employee*
// items it contains. The last item is our CEO, which gets destroyed as its // items it contains. The last item is our CEO, which gets destroyed as well.
// reference count goes to zero. The Java destructor runs, and is still
// able to call self.getName() since the underlying C++ object still
// exists. After this destructor runs the remaining C++ destructors run as
// usual to destroy the object.
list.delete(); list.delete();
System.out.println( "----------------------" ); System.out.println( "----------------------" );