Made changes to the C++ API in order to allow for proper error

propagation up to the toplevel error handler in BPY_txt_do_python_Text().

Before these changes were made, the operator() methods of predicates
and functions, for example, returned a value of various types such as
bool, double and Vec2f.  These returned values were not capable to
represent an error state in many cases.

Now the operator() methods always return 0 on normal exit and -1 on
error.  The original returned values are stored in the "result" member
variables of the predicate/function classes.

This means that if we have a code fragment like below:

  UnaryPredicate1D& pred;
  Interface1D& inter;
  if (pred(inter)) {
    /* do something */
  }

then we have to rewrite it as follows:

  UnaryPredicate1D& pred;
  Interface1D& inter;
  if (pred(inter) < 0)
    return -1; /* an error in pred() is propagated */
  if (pred.result) {
    /* do something */
  }

Suppose that pred is a user-defined predicate in Python, i.e. the predicate
is likely error-prone (especially when debugging the predicate).  The first
code fragment shown above prevents the proper error propagation because
the boolean return value of UnaryPredicate1D::operator() cannot inform the
occurrence of an error to the caller; the second code fragment can.

In addition to the operator() methods of predicates and functions, similar
improvements have been made to all other C++ API functions and methods that
are involved in the execution of user-defined Python code snippets.  Changes
in the signatures of functions and methods are summarized as follows (note
that all subclasses of listed classes are also subject to the changes).

Old signatures:
virtual void Iterator::increment();
virtual void Iterator::decrement();
virtual void ChainingIterator::init();
virtual ViewEdge * ChainingIterator::traverse(const AdjacencyIterator &it);
static void Operators::select(UnaryPredicate1D& pred);
static void Operators::chain(ViewEdgeInternal::ViewEdgeIterator& it,
	    UnaryPredicate1D& pred, UnaryFunction1D_void& modifier);
static void Operators::chain(ViewEdgeInternal::ViewEdgeIterator& it,
	    UnaryPredicate1D& pred);  
static void Operators::bidirectionalChain(ChainingIterator& it,
	    UnaryPredicate1D& pred);
static void Operators::bidirectionalChain(ChainingIterator& it);
static void Operators::sequentialSplit(UnaryPredicate0D& startingPred,
	    UnaryPredicate0D& stoppingPred, float sampling = 0);
static void Operators::sequentialSplit(UnaryPredicate0D& pred, float sampling = 0);
static void Operators::recursiveSplit(UnaryFunction0D<double>& func,
	    UnaryPredicate1D& pred, float sampling = 0);
static void Operators::recursiveSplit(UnaryFunction0D<double>& func,
	    UnaryPredicate0D& pred0d, UnaryPredicate1D& pred, float sampling = 0);
static void Operators::sort(BinaryPredicate1D& pred);
static void Operators::create(UnaryPredicate1D& pred, vector<StrokeShader*> shaders);
virtual bool UnaryPredicate0D::operator()(Interface0DIterator& it);
virtual bool BinaryPredicate0D::operator()(Interface0D& inter1, Interface0D& inter2);
virtual bool UnaryPredicate1D::operator()(Interface1D& inter);
virtual bool BinaryPredicate1D::operator()(Interface1D& inter1, Interface1D& inter2);
virtual void StrokeShader::shade(Stroke& ioStroke) const;
virtual T UnaryFunction0D::operator()(Interface0DIterator& iter);
virtual T UnaryFunction1D::operator()(Interface1D& inter);

New signatures:
virtual int Iterator::increment();
virtual int Iterator::decrement();
virtual int ChainingIterator::init();
virtual int ChainingIterator::traverse(const AdjacencyIterator &it);
static int Operators::select(UnaryPredicate1D& pred);
static int Operators::chain(ViewEdgeInternal::ViewEdgeIterator& it,
	   UnaryPredicate1D& pred, UnaryFunction1D_void& modifier);
static int Operators::chain(ViewEdgeInternal::ViewEdgeIterator& it,
	   UnaryPredicate1D& pred);  
static int Operators::bidirectionalChain(ChainingIterator& it,
	   UnaryPredicate1D& pred);
static int Operators::bidirectionalChain(ChainingIterator& it);
static int Operators::sequentialSplit(UnaryPredicate0D& startingPred,
	   UnaryPredicate0D& stoppingPred, float sampling = 0);
static int Operators::sequentialSplit(UnaryPredicate0D& pred, float sampling = 0);
static int Operators::recursiveSplit(UnaryFunction0D<double>& func,
	   UnaryPredicate1D& pred, float sampling = 0);
static int Operators::recursiveSplit(UnaryFunction0D<double>& func,
	   UnaryPredicate0D& pred0d, UnaryPredicate1D& pred, float sampling = 0);
static int Operators::sort(BinaryPredicate1D& pred);
static int Operators::create(UnaryPredicate1D& pred, vector<StrokeShader*> shaders);
virtual int UnaryPredicate0D::operator()(Interface0DIterator& it);
virtual int BinaryPredicate0D::operator()(Interface0D& inter1, Interface0D& inter2);
virtual int UnaryPredicate1D::operator()(Interface1D& inter);
virtual int BinaryPredicate1D::operator()(Interface1D& inter1, Interface1D& inter2);
virtual int StrokeShader::shade(Stroke& ioStroke) const;
virtual int UnaryFunction0D::operator()(Interface0DIterator& iter);
virtual int UnaryFunction1D::operator()(Interface1D& inter);

1 files changed, 26 insertions, 16 deletions

diff --git a/source/blender/freestyle/intern/stroke/ChainingIterators.h b/source/blender/freestyle/intern/stroke/ChainingIterators.h
index 1f33f99db67..1a40144d704 100755
--- a/source/blender/freestyle/intern/stroke/ChainingIterators.h
+++ b/source/blender/freestyle/intern/stroke/ChainingIterators.h
@@ -102,10 +102,11 @@ public:
     increment();
     return tmp;
   }
-  virtual void increment();
+  virtual int increment();
 
-  virtual void decrement(){
+  virtual int decrement(){
     cerr << "Warning: method decrement() not implemented" << endl;
+	return 0;
   }
 
 protected:
@@ -138,6 +139,7 @@ protected:
   
 public:
 	
+	ViewEdge *result;
 	PyObject *py_c_it;
 	
   /*! Builds a Chaining Iterator from the first ViewEdge used for iteration
@@ -183,15 +185,17 @@ public:
    *  history information that you 
    *  might want to keep.  
    */
-  virtual void init() {
+  virtual int init() {
 	string name( py_c_it ? PyString_AsString(PyObject_CallMethod(py_c_it, "getExactTypeName", "")) : getExactTypeName() );
 	
 	if( py_c_it && PyObject_HasAttrString(py_c_it, "init") ) {
-		Director_BPy_ChainingIterator_init( py_c_it );
+		if (Director_BPy_ChainingIterator_init( py_c_it ) < 0) {
+			return -1;
+		}
 	} else {
-		cerr << "Warning: " << name << " method init() not implemented" << endl;
+		cerr << "Warning: " << name << " init() method not implemented" << endl;
 	}
-	
+	return 0;
   }
   
   /*! This method iterates over the potential next 
@@ -205,15 +209,17 @@ public:
    *    The Adjacency iterator reflects the restriction 
    *    rules by only iterating over the valid ViewEdges.
    */
-  virtual ViewEdge * traverse(const AdjacencyIterator &it){
+  virtual int traverse(const AdjacencyIterator &it){
 	string name( py_c_it ? PyString_AsString(PyObject_CallMethod(py_c_it, "getExactTypeName", "")) : getExactTypeName() );
 	
 	if( py_c_it && PyObject_HasAttrString(py_c_it, "traverse") ) {
-		return Director_BPy_ChainingIterator_traverse(py_c_it, const_cast<AdjacencyIterator &>(it) );
+		if (Director_BPy_ChainingIterator_traverse(py_c_it, const_cast<AdjacencyIterator &>(it), &result ) < 0) {
+			return -1;
+		}
 	} else {
-	    cerr << "Warning: the " << name << " traverse method was not defined" << endl;
-	    return 0;
+	    cerr << "Warning: the " << name << " traverse() method not defined" << endl;
 	}
+    return 0;
   }
 
   /* accessors */
@@ -244,8 +250,8 @@ public:
   }
   
   /* increments.*/
-  virtual void increment() ;
-  virtual void decrement() ;
+  virtual int increment() ;
+  virtual int decrement() ;
 };
 
 //
@@ -294,10 +300,12 @@ public:
    *  followed next.
    *  When reaching the end of a chain, 0 is returned.
    */
-  virtual ViewEdge * traverse(const AdjacencyIterator& it);
+  virtual int traverse(const AdjacencyIterator& it);
 
 	/*! Inits the iterator context */ 
-	virtual void init() {}
+  virtual int init() {
+    return 0;
+  }
 };
 
 //
@@ -392,10 +400,12 @@ public:
    *  followed next.
    *  When reaching the end of a chain, 0 is returned.
    */
-  virtual ViewEdge * traverse(const AdjacencyIterator &it);
+  virtual int traverse(const AdjacencyIterator &it);
 
 	/*! Inits the iterator context */ 
-	virtual void init() {}
+  virtual int init() {
+	return 0;
+  }
  
 };