Provide a more convenient way to declare internal C properties.

Cython/Compiler/PyrexTypes.py

@@ -1693,19 +1693,13 @@ class PythranExpr(CType):
             scope.directives = {}
 
             scope.declare_var("ndim", c_long_type, pos=None, cname="value", is_cdef=True)
-
-            shape_type = c_ptr_type(c_long_type)
-            shape_entry = scope.declare_property(
-                "shape", doc="Pythran array shape", ctype=shape_type, pos=None)
-            shape_entry.scope.declare_cfunction(
-                name="shape",
-                type=CFuncType(shape_type, [CFuncTypeArg("self", self, pos=None)], nogil=True),
-                cname="__Pyx_PythranShapeAccessor",
-                visibility='extern',
-                pos=None,
+            scope.declare_cproperty(
+                "shape", c_ptr_type(c_long_type), "__Pyx_PythranShapeAccessor",
+                doc="Pythran array shape",
+                visibility="extern",
+                nogil=True,
             )
 
-
         return True
 
     def __eq__(self, other):

Cython/Compiler/Symtab.py

@@ -2412,6 +2412,27 @@ class CClassScope(ClassScope):
         self.property_entries.append(entry)
         return entry
 
+    def declare_cproperty(self, name, type, cfunc_name, doc=None, pos=None, visibility='extern',
+                          nogil=False, with_gil=False, exception_value=None, exception_check=False):
+        """Internal convenience method to declare a C property function in one go.
+        """
+        property_entry = self.declare_property(name, doc=doc, ctype=type, pos=pos)
+        cfunc_entry = property_entry.scope.declare_cfunction(
+            name=name,
+            type=PyrexTypes.CFuncType(
+                type,
+                [PyrexTypes.CFuncTypeArg("self", self.parent_type, pos=None)],
+                nogil=nogil,
+                with_gil=with_gil,
+                exception_value=exception_value,
+                exception_check=exception_check,
+            ),
+            cname=cfunc_name,
+            visibility=visibility,
+            pos=pos,
+        )
+        return property_entry, cfunc_entry
+
     def declare_inherited_c_attributes(self, base_scope):
         # Declare entries for all the C attributes of an
         # inherited type, with cnames modified appropriately