[Vala] sentinel patch

[Sam Liddicott <sam liddicott com>]

This patch allows sentinels to be specified on a class and apply to all
varargs methods of that class and subclasses.

it also allows an empty string to be specified
[CCode (sentinel="")]

which results in no sentinel argument being emitted.

I find it useful so I can declare access to macro's of a c library
without vala worrying about the arguments matching up; as traditionally
macros can be very liberal about arguments.

to use Samba's DLIST_ADD, I can use DLIST.ADD declared below:

    [Compact]
    [CCode (cprefix="DLIST_")]
    [CCode (sentinel="")]
    class DLIST {
        public static void REMOVE(...);
        public static void ADD(...);
    }

Sam

Index: vala/valaclass.vala
===================================================================
--- vala/valaclass.vala (revision 1755)
+++ vala/valaclass.vala (working copy)
@@ -88,10 +115,30 @@
         */
        public bool has_private_fields { get; private set; }
 
+       /**
+        * default sentinel for varargs methods of this class
+        */
+       public string? sentinel {
+               get {
+                       if (_sentinel != null) {
+                               return _sentinel;
+                       }
+                       if (base_class != null) {
+                               return base_class.sentinel;
+                       }
+                       return null;
+               }
+
+               set {
+                       _sentinel = value;
+               }
+       }
+
        private string cname;
        private string const_cname;
        private string lower_case_cprefix;
        private string lower_case_csuffix;
+       private string _sentinel;
        private string type_id;
        private string ref_function;
        private string unref_function;
@@ -580,8 +634,11 @@
                if (a.has_argument ("type_check_function")) {
                        type_check_function = a.get_string ("type_check_function");
                }
+               if (a.has_argument ("sentinel")) {
+                       sentinel = a.get_string ("sentinel");
+               }
        }
-       
+
        /**
         * Process all associated attributes.
         */
Index: vala/valamethod.vala
===================================================================
--- vala/valamethod.vala        (revision 1755)
+++ vala/valamethod.vala        (working copy)
@@ -82,9 +82,14 @@
        public string sentinel {
                get {
                        if (_sentinel == null) {
+                               if (parent_symbol != null && parent_symbol is Class) {
+                                       var s = (parent_symbol as Class).sentinel;
+                                       if (s != null) {
+                                               return s;
+                                       }
+                               }
                                return DEFAULT_SENTINEL;
                        }
-
                        return _sentinel;
                }
 
Index: gobject/valaccodeinvocationexpressionbinding.vala
===================================================================
--- gobject/valaccodeinvocationexpressionbinding.vala   (revision 1755)
+++ gobject/valaccodeinvocationexpressionbinding.vala   (working copy)
@@ -392,7 +392,7 @@
                if (ellipsis) {
                        /* ensure variable argument list ends with NULL
                         * except when using printf-style arguments */
-                       if ((m == null || !m.printf_format)) {
+                       if (!m.printf_format && m.sentinel != "") {
                                carg_map.set (codegen.get_param_pos (-1, true), new CCodeConstant 
(m.sentinel));
                        }
                } else if (itype is DelegateType) {