New example showing use of %catchs and %

git-svn-id: https://swig.svn.sourceforge.net/svnroot/swig/trunk/SWIG@8355 626c5289-ae23-0410-ae9c-e8d60b6d4f22

Examples/ruby/exception_class/Makefile

@@ -0,0 +1,19 @@
+TOP        = ../..
+SWIG       = $(TOP)/../preinst-swig
+CXXSRCS    = 
+TARGET     = example
+INTERFACE  = example.i
+LIBS       = -lm
+
+all::
+	$(MAKE) -f $(TOP)/Makefile CXXSRCS='$(CXXSRCS)' SWIG='$(SWIG)' \
+	TARGET='$(TARGET)' INTERFACE='$(INTERFACE)' ruby_cpp
+
+static::
+	$(MAKE) -f $(TOP)/Makefile CXXSRCS='$(CXXSRCS)' SWIG='$(SWIG)' \
+	TARGET='myruby' INTERFACE='$(INTERFACE)' ruby_cpp_static
+
+clean::
+	$(MAKE) -f $(TOP)/Makefile ruby_clean
+
+check: all

Examples/ruby/exception_class/example.h

@@ -0,0 +1,51 @@
+/* File : example.h */
+
+// A simple exception
+class EmptyError { };
+class FullError { 
+ public:
+  int maxsize;
+  FullError(int m) : maxsize(m) { }
+};
+
+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;
+  }
+};
+
+
+
+
+
+
+  

Examples/ruby/exception_class/example.i

@@ -0,0 +1,45 @@
+/* This example illustrates the use of the %exceptionclass feature.  By
+   default, if a method has a throws specification then SWIG will generate
+   code to catch the exception and pass it on the scripting language.
+   
+   If a method does not have a throws specification, but does throw 
+   an exception, then the %exceptionclass feature can be used to tell
+   SWIG about the exception class so it can be properly added to Ruby.
+   This is done by making the exception class inherit from rb_eRuntimeError.*/
+
+%module example
+
+%{
+#include "example.h"
+%}
+
+
+/* The EmpytError doesn't appear in a throw declaration, and hence
+  we need to tell SWIG that the dequeue method throws it.  This can
+  now be done via the %catchs feature. */
+%catchs(EmptyError) *::dequeue();
+
+
+/* What the catchs clause is doing under the covers is this:
+
+%exceptionclass EmptyError;
+
+%exception *::dequeue {
+   try {
+      $action
+   } catch(EmptyError& e) {
+		  // Create a new instance of the EmptyError, wrap it as a Ruby object that Ruby owns,
+		  // and return it as the exception.  For this to work EmtpyError must inherit from
+		  // a standard Ruby exception class such as rb_eRuntimeError.  SWIG automatically does
+		  // this when the class is marked as %exceptionclass or is a throws specification.
+ 		%raise(SWIG_NewPointerObj(new EmptyError(e), SWIGTYPE_p_EmptyError, SWIG_POINTER_OWN), "EmptyError", SWIGTYPE_p_EmptyError);
+   }
+}
+*/
+
+/* Grab the original header file */
+%include "example.h"
+
+/* Instantiate a few templates */
+%template(IntQueue) Queue<int>;
+%template(DoubleQueue) Queue<double>;

Examples/ruby/exception_class/runme.rb

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+require 'example'
+
+q = Example::IntQueue.new(10)
+
+puts "Inserting items into intQueue"
+
+begin
+    0.upto(100) do |i|
+    q.enqueue(i)
+  end
+rescue Example::FullError => e
+  puts "Maxsize is: #{e.maxsize}"
+end
+
+puts "Removing items"
+
+begin
+  loop do
+    q.dequeue()
+  end
+rescue Example::EmptyError => e
+  ## do nothing
+end
+
+q = Example::DoubleQueue.new(1000)
+
+puts "Inserting items into doubleQueue"
+
+begin
+  0.upto(100) do |i|
+    q.enqueue(i*1.5)
+  end
+rescue Example::FullError => e
+  puts "Maxsize is: #{e.maxsize}"
+end
+
+puts "Removing items"
+
+begin
+  loop do
+    q.dequeue()
+  end
+rescue Example::EmptyError => e
+  # do nothing
+end