Fix handling of "default" typemap in Python.

Use "compact" arguments form for the function if "default" typemap is defined
for any of its arguments to allow omitting this argument when calling it from
Python.

Closes #377.

CHANGES.current

@@ -5,6 +5,9 @@ See the RELEASENOTES file for a summary of changes in each release.
 Version 3.0.6 (in progress)
 ===========================
 
+2015-04-23: vadz
+            [Python] Make "default" typemap work again (#330, #377).
+
 2015-04-23: vadz
             [Python] Fix the use of default values for the pointer types (#365, #376).
 

Examples/test-suite/default_args.i

@@ -114,6 +114,8 @@
 %rename(renamed2arg) Foo::renameme(int x) const;
 %rename(renamed1arg) Foo::renameme() const;
 
+%typemap(default) double* null_by_default "$1=0;";
+
 %inline %{
   typedef void* MyHandle;
 
@@ -144,6 +146,8 @@
       // test default values for pointer arguments
       int double_if_void_ptr_is_null(int n, void* p = NULL) { return p ? n : 2*n; }
       int double_if_handle_is_null(int n, MyHandle h = 0) { return h ? n : 2*n; }
+      int double_if_dbl_ptr_is_null(int n, double* null_by_default)
+        { return null_by_default ? n : 2*n; }
   };
   int Foo::bar = 1;
   int Foo::spam = 2;

Examples/test-suite/python/default_args_runme.py

@@ -43,6 +43,12 @@ def run(module_name):
   if f.double_if_handle_is_null(5) != 10:
     raise RuntimeError
 
+  if f.double_if_dbl_ptr_is_null(6, None) != 12:
+    raise RuntimeError
+
+  if f.double_if_dbl_ptr_is_null(7) != 14:
+    raise RuntimeError
+
   try:
     f = default_args.Foo(1)
     error = 1

Source/Modules/python.cxx

@@ -1999,9 +1999,9 @@ public:
    *    at C++ code level where they can always be handled.
    * ------------------------------------------------------------ */
   bool is_representable_as_pyargs(Node *n) {
-    bool is_representable = true;
-
     ParmList *plist = CopyParmList(Getattr(n, "parms"));
+    Swig_typemap_attach_parms("default", plist, NULL);
+
     Parm *p;
     Parm *pnext;
 
@@ -2017,16 +2017,23 @@ public:
       if (!pnext) {
 	pnext = nextSibling(p);
       }
+
+      // "default" typemap can contain arbitrary C++ code, so while it could, in
+      // principle, be possible to examine it and check if it's just something
+      // simple of the form "$1 = expression" and then use convertValue() to
+      // check if expression can be used in Python, but for now we just
+      // pessimistically give up and prefer to handle this at C++ level only.
+      if (Getattr(p, "tmap:default"))
+	return false;
+
       if (String *value = Getattr(p, "value")) {
 	String *type = Getattr(p, "type");
-	if (!convertValue(value, type)) {
-	  is_representable = false;
-	  break;
-	}
+	if (!convertValue(value, type))
+	  return false;
       }
     }
 
-    return is_representable;
+    return true;
   }