[dia] PyDia: support DiagramData.diagram (kind of dynamic cast)

[Hans Breuer <hans src gnome org>]

commit 5e9d0490107542e2a5852610bb36da385f26707d
Author: Hans Breuer <hans breuer org>
Date:   Mon Apr 21 16:52:20 2014 +0200

    PyDia: support DiagramData.diagram (kind of dynamic cast)
    
    The DiagramData object passed to plug-ins usually is-a Diagram, too.
    The new read-only attribute can be used to access methods only
    implemented by the latter.

 plug-ins/python/pydia-diagramdata.c |    9 +++++++++
 1 files changed, 9 insertions(+), 0 deletions(-)
---
diff --git a/plug-ins/python/pydia-diagramdata.c b/plug-ins/python/pydia-diagramdata.c
index d8de53e..4dc3f0c 100644
--- a/plug-ins/python/pydia-diagramdata.c
+++ b/plug-ins/python/pydia-diagramdata.c
@@ -32,6 +32,7 @@
 #include <structmember.h> /* PyMemberDef */
 
 #include "app/diagram.h"
+#include "pydia-diagram.h" /* support dynamic_cast */
 
 PyObject *
 PyDiaDiagramData_New(DiagramData *dd)
@@ -333,6 +334,8 @@ static PyMemberDef PyDiaDiagramData_Members[] = {
       "List of real: vertical guides."},
     { "selected", T_INVALID, 0, RESTRICTED|READONLY,
       "List of Object: current selection."},
+    { "diagram", T_INVALID, 0, RESTRICTED|READONLY,
+      "This data objects Diagram or None"},
     { NULL }
 };
 
@@ -409,6 +412,12 @@ PyDiaDiagramData_GetAttr(PyDiaDiagramData *self, gchar *attr)
            PyTuple_SetItem(ret, i, PyDiaObject_New((DiaObject *)tmp->data));
        return ret;
     }
+    else if (!strcmp(attr, "diagram")) {
+       if (DIA_IS_DIAGRAM (self->data))
+           return PyDiaDiagram_New (DIA_DIAGRAM (self->data));
+       Py_INCREF(Py_None);
+       return Py_None;
+    }
 
     return Py_FindMethod(PyDiaDiagramData_Methods, (PyObject *)self, attr);
 }