ec75a4e978
git-svn-id: https://swig.svn.sourceforge.net/svnroot/swig/trunk/SWIG@7633 626c5289-ae23-0410-ae9c-e8d60b6d4f22
113 lines
3.3 KiB
OpenEdge ABL
113 lines
3.3 KiB
OpenEdge ABL
/* This is a rather sophisticated example that illustrates exception handling,
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templates, and shadow classes.
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(i) The %exception directive is used to attach exception handlers
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to specific methods.
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(ii) Exception classes are automatically converted to shadow class
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objects.
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(iii) The %template directive is used to expand the templates
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*/
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%module example
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%{
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#include "example.h"
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%}
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/* Define some exception handlers for specific methods. In
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the header file, the enqueue method throws FullError and
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the dequeue method throws EmptyError. Since we don't
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want to define an exception handler for everything, we
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simply write a handler each method individually.
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Note: the *::enqueue syntax means that we simply define
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the handler for any class with this method defined.
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*/
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/*
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First we need to 'disable' the default swig throw mechanism for the
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FullError class. We do this by rethrowing the exception.
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Note that this is necessary since the class appears in a throw
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declaration:
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void enqueue(T x) throw(FullError);
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hence, swig recognizes it as an exception class and it will generate
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the necessary code to catch it and rethrow it to the python side.
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*/
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%typemap(throws) FullError "(void)$1; throw;";
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%exception *::enqueue {
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try {
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$action
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} catch(FullError& e) {
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FullError *ecopy = new FullError(e);
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PyObject *err = SWIG_NewPointerObj(ecopy, SWIGTYPE_p_FullError, 1);
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PyErr_SetObject((PyObject *) SWIGTYPE_p_FullError->clientdata, err);
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return NULL;
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}
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}
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/* Some notes about the code above:
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(0) $action gets replaced with the actual method call.
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(1) We are going to return a copy of the exception object (FullError)
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to pass back to the Python interpreter. This is why the copy
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constructor is being called.
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(2) The SWIG_NewPointerObj() call automatically wraps the exception object
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into a shadow class. The SWIGTYPE_p_FullError is the type-descriptor
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used for type checking. The "1" indicates that Python will have
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ownership of the resulting object.
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(3) The PyErr_SetObject call sets the Python exception. However,
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the SWIGTYPE_p_FullError->clientdata reference may not be
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obvious. This is actually the Python shadow class object
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for FullError. Recall that in Python, exceptions are defined
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as classes. Therefore, this works perfectly as the argument to
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PyErr_SetObject()! A neat trick perhaps.
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*/
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/*
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Now, the EmpytError doesn't appear in a throw declaration, and hence
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we need to 'mark' it as an exception class. In python, classes that
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are used as exception are 'special', and need to be wrapped as
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'classic' ones.
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This is a python issue, and if you don't mark the class, you will
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see 'interesting' behaviours at the python side.
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*/
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%exceptionclass EmptyError;
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%exception *::dequeue {
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try {
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$action
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} catch(EmptyError& e) {
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EmptyError *ecopy = new EmptyError(e);
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PyObject *err = SWIG_NewPointerObj(ecopy, SWIGTYPE_p_EmptyError, 1);
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PyErr_SetObject((PyObject *) SWIGTYPE_p_EmptyError->clientdata, err);
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return NULL;
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}
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}
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/* Grab the original header file */
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%include "example.h"
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/* Instantiate a few templates */
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%template(intQueue) Queue<int>;
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%template(doubleQueue) Queue<double>;
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