Memory management fixes and comment corrections
git-svn-id: https://swig.svn.sourceforge.net/svnroot/swig/trunk@5656 626c5289-ae23-0410-ae9c-e8d60b6d4f22
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1 changed files with 14 additions and 21 deletions
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@ -10,6 +10,10 @@ class CEO extends Manager {
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public String getPosition() {
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public String getPosition() {
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return "CEO";
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return "CEO";
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}
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}
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// Public method to stop the SWIG proxy base class from thinking it owns the underlying C++ memory.
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public void disownMemory() {
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swigCMemOwn = false;
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}
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}
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}
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@ -26,9 +30,9 @@ public class main {
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public static void main(String argv[])
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public static void main(String argv[])
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{
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{
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// Create an instance of our employee extension class, CEO. The calls to
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// Create an instance of CEO, a class derived from the Java proxy of the
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// getName() and getPosition() are standard, the call to getTitle() uses
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// underlying C++ class. The calls to getName() and getPosition() are standard,
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// the director wrappers to call CEO.getPosition. e = CEO("Alice")
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// the call to getTitle() uses the director wrappers to call CEO.getPosition().
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CEO e = new CEO("Alice");
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CEO e = new CEO("Alice");
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System.out.println( e.getName() + " is a " + e.getPosition() );
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System.out.println( e.getName() + " is a " + e.getPosition() );
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@ -41,29 +45,23 @@ public class main {
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EmployeeList list = new EmployeeList();
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EmployeeList list = new EmployeeList();
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// EmployeeList owns its items, so we must surrender ownership of objects
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// EmployeeList owns its items, so we must surrender ownership of objects we add.
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// we add. This involves first calling the __disown__ method to tell the
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e.disownMemory();
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// C++ director to start reference counting. We reassign the resulting
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// weakref.proxy to e so that no hard references remain. This can also be
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// done when the object is constructed, as in: e =
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// CEO("Alice").__disown__()
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// e = e.__disown__();
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list.addEmployee(e);
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list.addEmployee(e);
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System.out.println( "----------------------" );
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System.out.println( "----------------------" );
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// Now we access the first four items in list (three are C++ objects that
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// Now we access the first four items in list (three are C++ objects that
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// EmployeeList's constructor adds, the last is our CEO). The virtual
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// EmployeeList's constructor adds, the last is our CEO). The virtual
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// methods of all these instances are treated the same. For items 0, 1, and
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// methods of all these instances are treated the same. For items 0, 1, and
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// 2, both all methods resolve in C++. For item 3, our CEO, getTitle calls
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// 2, all methods resolve in C++. For item 3, our CEO, getTitle calls
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// getPosition which resolves in Java. The call to getPosition is
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// getPosition which resolves in Java. The call to getPosition is
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// slightly different, however, from the e.getPosition() call above, since
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// slightly different, however, because of the overidden getPosition() call, since
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// now the object reference has been "laundered" by passing through
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// now the object reference has been "laundered" by passing through
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// EmployeeList as an Employee*. Previously, Java resolved the call
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// EmployeeList as an Employee*. Previously, Java resolved the call
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// immediately in CEO, but now Java thinks the object is an instance of
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// immediately in CEO, but now Java thinks the object is an instance of
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// class Employee (actually EmployeePtr). So the call passes through the
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// class Employee. So the call passes through the
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// Employee proxy class and on to the C wrappers and C++ director,
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// Employee proxy class and on to the C wrappers and C++ director,
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// eventually ending up back at the CEO implementation of getPosition().
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// eventually ending up back at the Java CEO implementation of getPosition().
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// The call to getTitle() for item 3 runs the C++ Employee::getTitle()
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// The call to getTitle() for item 3 runs the C++ Employee::getTitle()
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// method, which in turn calls getPosition(). This virtual method call
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// method, which in turn calls getPosition(). This virtual method call
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// passes down through the C++ director class to the Java implementation
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// passes down through the C++ director class to the Java implementation
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@ -78,12 +76,7 @@ public class main {
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System.out.println( "----------------------" );
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System.out.println( "----------------------" );
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// Time to delete the EmployeeList, which will delete all the Employee*
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// Time to delete the EmployeeList, which will delete all the Employee*
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// items it contains. The last item is our CEO, which gets destroyed as its
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// items it contains. The last item is our CEO, which gets destroyed as well.
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// reference count goes to zero. The Java destructor runs, and is still
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// able to call self.getName() since the underlying C++ object still
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// exists. After this destructor runs the remaining C++ destructors run as
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// usual to destroy the object.
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list.delete();
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list.delete();
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System.out.println( "----------------------" );
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System.out.println( "----------------------" );
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