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authorLorry Tar Creator <lorry-tar-importer@baserock.org>2009-08-18 20:56:02 +0000
committerLorry <lorry@roadtrain.codethink.co.uk>2012-09-25 16:59:08 +0000
commit9f8a09ed743cedd9547bf0661d518647966ab114 (patch)
tree9c7803d3b27a8ec22e91792ac7f7932efa128b20 /Examples/python/exceptproxy
downloadswig-tarball-master.tar.gz
Imported from /srv/lorry/lorry-area/swig-tarball/swig-1.3.40.tar.gz.HEADswig-1.3.40master
Diffstat (limited to 'Examples/python/exceptproxy')
-rw-r--r--Examples/python/exceptproxy/Makefile22
-rw-r--r--Examples/python/exceptproxy/example.h54
-rw-r--r--Examples/python/exceptproxy/example.i114
-rw-r--r--Examples/python/exceptproxy/runme.py45
4 files changed, 235 insertions, 0 deletions
diff --git a/Examples/python/exceptproxy/Makefile b/Examples/python/exceptproxy/Makefile
new file mode 100644
index 0000000..ba5c798
--- /dev/null
+++ b/Examples/python/exceptproxy/Makefile
@@ -0,0 +1,22 @@
+TOP = ../..
+SWIG = $(TOP)/../preinst-swig
+CXXSRCS =
+TARGET = example
+INTERFACE = example.i
+LIBS = -lm
+SWIGOPT =
+
+all::
+ $(MAKE) -f $(TOP)/Makefile CXXSRCS='$(CXXSRCS)' SWIG='$(SWIG)' \
+ SWIGOPT='$(SWIGOPT)' TARGET='$(TARGET)' INTERFACE='$(INTERFACE)' python_cpp
+
+static::
+ $(MAKE) -f $(TOP)/Makefile CXXSRCS='$(CXXSRCS)' SWIG='$(SWIG)' \
+ SWIGOPT='$(SWIGOPT)' TARGET='mypython' INTERFACE='$(INTERFACE)' python_cpp_static
+
+clean::
+ $(MAKE) -f $(TOP)/Makefile python_clean
+ rm -f $(TARGET).py
+
+check: all
+ $(MAKE) -f $(TOP)/Makefile python_run
diff --git a/Examples/python/exceptproxy/example.h b/Examples/python/exceptproxy/example.h
new file mode 100644
index 0000000..ec7107a
--- /dev/null
+++ b/Examples/python/exceptproxy/example.h
@@ -0,0 +1,54 @@
+/* File : example.h */
+
+// A simple exception
+class EmptyError { };
+class FullError {
+ public:
+ int maxsize;
+ FullError(int m) : maxsize(m) { }
+};
+
+#if defined(_MSC_VER)
+ #pragma warning(disable: 4290) // C++ exception specification ignored except to indicate a function is not __declspec(nothrow)
+#endif
+
+template<typename T> class Queue {
+ int maxsize;
+ T *items;
+ int nitems;
+ int last;
+ public:
+ Queue(int size) {
+ maxsize = size;
+ items = new T[size];
+ nitems = 0;
+ last = 0;
+ }
+ ~Queue() {
+ delete [] items;
+ }
+ void enqueue(T x) throw(FullError) {
+ if (nitems == maxsize) {
+ throw FullError(maxsize);
+ }
+ items[last] = x;
+ last = (last + 1) % maxsize;
+ nitems++;
+ }
+ T dequeue() {
+ T x;
+ if (nitems == 0) throw EmptyError();
+ x = items[(last + maxsize - nitems) % maxsize];
+ nitems--;
+ return x;
+ }
+ int length() {
+ return nitems;
+ }
+};
+
+
+#if defined(_MSC_VER)
+ #pragma warning(default: 4290) // C++ exception specification ignored except to indicate a function is not __declspec(nothrow)
+#endif
+
diff --git a/Examples/python/exceptproxy/example.i b/Examples/python/exceptproxy/example.i
new file mode 100644
index 0000000..4a1e0ba
--- /dev/null
+++ b/Examples/python/exceptproxy/example.i
@@ -0,0 +1,114 @@
+/* This is a rather sophisticated example that illustrates exception handling,
+ templates, and proxy classes.
+
+ (i) The %exception directive is used to attach exception handlers
+ to specific methods.
+
+ (ii) Exception classes are automatically converted to proxy class
+ objects.
+
+ (iii) The %template directive is used to expand the templates
+*/
+
+%module example
+
+%{
+#include "example.h"
+%}
+
+/* Define some exception handlers for specific methods. In
+ the header file, the enqueue method throws FullError and
+ the dequeue method throws EmptyError. Since we don't
+ want to define an exception handler for everything, we
+ simply write a handler each method individually.
+
+ Note: the *::enqueue syntax means that we simply define
+ the handler for any class with this method defined.
+*/
+
+/*
+ First we need to 'disable' the default swig throw mechanism for the
+ FullError class. We do this by rethrowing the exception.
+
+ Note that this is necessary since the class appears in a throw
+ declaration:
+
+
+ void enqueue(T x) throw(FullError);
+
+ hence, swig recognizes it as an exception class and it will generate
+ the necessary code to catch it and rethrow it to the python side.
+
+*/
+%typemap(throws) FullError "(void)$1; throw;";
+
+
+%exception *::enqueue {
+ try {
+ $action
+ } catch(FullError& e) {
+ FullError *ecopy = new FullError(e);
+ PyObject *err = SWIG_NewPointerObj(ecopy, SWIGTYPE_p_FullError, 1);
+ PyErr_SetObject(SWIG_Python_ExceptionType(SWIGTYPE_p_FullError), err);
+ SWIG_fail;
+ }
+}
+
+/* Some notes about the code above:
+
+ (0) $action gets replaced with the actual method call.
+
+ (1) We are going to return a copy of the exception object (FullError)
+ to pass back to the Python interpreter. This is why the copy
+ constructor is being called.
+
+ (2) The SWIG_NewPointerObj() call automatically wraps the exception object
+ into a proxy class. The SWIGTYPE_p_FullError is the type-descriptor
+ used for type checking. The "1" indicates that Python will have
+ ownership of the resulting object.
+
+ (3) The PyErr_SetObject call sets the Python exception. However,
+ the SWIGTYPE_p_FullError->clientdata reference may not be
+ obvious. This is actually the Python proxy class object
+ for FullError. Recall that in Python, exceptions are defined
+ as classes. Therefore, this works perfectly as the argument to
+ PyErr_SetObject()! A neat trick perhaps.
+*/
+
+/*
+ Now, the EmpytError doesn't appear in a throw declaration, and hence
+ we need to 'mark' it as an exception class. In python, classes that
+ are used as exception are 'special', and need to be wrapped as
+ 'classic' ones.
+
+ This is a python issue, and if you don't mark the class, you will
+ see 'interesting' behaviours at the python side.
+
+
+*/
+%exceptionclass EmptyError;
+%exceptionclass FullError;
+
+%exception *::dequeue {
+ try {
+ $action
+ } catch(EmptyError& e) {
+ EmptyError *ecopy = new EmptyError(e);
+ PyObject *err = SWIG_NewPointerObj(ecopy, SWIGTYPE_p_EmptyError, 1);
+ PyErr_SetObject(SWIG_Python_ExceptionType(SWIGTYPE_p_EmptyError), err);
+ SWIG_fail;
+ }
+}
+
+/* Grab the original header file */
+%include "example.h"
+
+/* Instantiate a few templates */
+
+%template(intQueue) Queue<int>;
+%template(doubleQueue) Queue<double>;
+
+
+
+
+
diff --git a/Examples/python/exceptproxy/runme.py b/Examples/python/exceptproxy/runme.py
new file mode 100644
index 0000000..a2ae555
--- /dev/null
+++ b/Examples/python/exceptproxy/runme.py
@@ -0,0 +1,45 @@
+# file: runme.py
+import example
+
+q = example.intQueue(10)
+
+print "Inserting items into intQueue"
+
+try:
+ for i in range(0,100):
+ q.enqueue(i)
+except example.FullError,e:
+ print "Maxsize is", e.maxsize
+
+print "Removing items"
+
+try:
+ while 1:
+ q.dequeue()
+except example.EmptyError,e:
+ pass
+
+
+q = example.doubleQueue(1000)
+
+print "Inserting items into doubleQueue"
+
+try:
+ for i in range(0,10000):
+ q.enqueue(i*1.5)
+except example.FullError,e:
+ print "Maxsize is", e.maxsize
+
+print "Removing items"
+
+try:
+ while 1:
+ q.dequeue()
+except example.EmptyError,e:
+ pass
+
+
+
+
+
+