How It Works - Writing Extension Modules

• Subclass PyObject
Remember, Java has single implemenation inheritance (but multiple interface inheritance)
• If implementing a module, add to org.python.modules.Setup
This might change
• Java<=>Python datatype mapping in both directions
This is not really extensible right now unless you implement the class yourself.

Sample code

 public void __setattr__(String name, PyObject value) {

   if ("arraysize".equals(name)) {
     this.arraysize = value.__int__().getValue();
   } else if ("softspace".equals(name)) {
     this.softspace = value.__int__().getValue();
   } else if ("datahandler".equals(name)) {
     this.datahandler = (DataHandler)value.__tojava__(DataHandler.class);
   } else {
     super.__setattr__(name, value);
   }
 }

 /**
  * Gets the value of the attribute name.
  *
  * @param name
  * @return the attribute for the given name
  */
 public PyObject __findattr__(String name) {

   if ("arraysize".equals(name)) {
     return Py.newInteger(arraysize);
   } else if ("softspace".equals(name)) {
     return Py.newInteger(softspace);
   } else if ("__methods__".equals(name)) {
     return __methods__;
   } else if ("__members__".equals(name)) {
     return __members__;
   } else if ("description".equals(name)) {
     return this.fetch.description;
   } else if ("rowcount".equals(name)) {
     return Py.newInteger(this.fetch.rowcount);
   } else if ("rownumber".equals(name)) {
     int rn = this.fetch.rownumber;
     return (rn < 0) ? Py.None : Py.newInteger(rn);
   } else if ("warnings".equals(name)) {
     return warnings;
   } else if ("lastrowid".equals(name)) {
     return lastrowid;
   } else if ("updatecount".equals(name)) {
     return updatecount;
   } else if ("datahandler".equals(name)) {
     return Py.java2py(this.datahandler);
   } else if ("dynamic".equals(name)) {
     return this.dynamicFetch ? Py.One : Py.Zero;
   } else if ("connection".equals(name)) {
     return this.connection;
   } else if ("closed".equals(name)) {
     return Py.newBoolean(closed);
   } else if ("callproc".equals(name)) {
     try {
       // dynamically decide on the the attribute based on the driver
       if (!getMetaData().supportsStoredProcedures()) {
           return null;
       }
     } catch (Throwable t) {}
   }

   return super.__findattr__(name);
 }

/**
  * Returns an iteratable object.
  *
  * @return PyObject
  *
  * @since Jython 2.2, DB API 2.0+
  */
 public PyObject __iter__() {
   return this;
 }

 /**
  * Returns the next row from the currently executing SQL statement
  * using the same semantics as .fetchone().  A StopIteration
  * exception is raised when the result set is exhausted for Python
  * versions 2.2 and later.
  *
  * @return PyObject
  *
  * @since Jython 2.2, DB API 2.0+
  */
 public PyObject next() {
   PyObject row = __iternext__();
   if (row == null) {
     throw Py.StopIteration("");
   }
   return row;
 }

 /**
  * Return the next element of the sequence that this is an iterator
  * for. Returns null when the end of the sequence is reached.
  *
  * @since Jython 2.2
  *
  * @return PyObject
  */
 public PyObject __iternext__() {
   PyObject row = fetchone();
   return row.__nonzero__() ? row : null;
 }

ExtensionModule.txt