X-Git-Url: https://git.distorted.org.uk/~mdw/sod/blobdiff_plain/7d21069e791a4d164c1eb1fc4f1ae661fe08ffbe..d83a91c663ced211bb7e4509f800859c3fa086e9:/lib/sod.h

diff --git a/lib/sod.h b/lib/sod.h
index 594e343..8270895 100644
--- a/lib/sod.h
+++ b/lib/sod.h
@@ -53,7 +53,7 @@ struct sod_vtable {
  * these.
  */
 struct sod_instance {
-  struct sod_vtable *_vt;		/* Pointer to (chain's) vtable */
+  const struct sod_vtable *_vt;		/* Pointer to (chain's) vtable */
 };
 
 /* Information about a particular chain of superclasses.  In each class,
@@ -124,6 +124,18 @@ struct sod_chain {
   ((struct cls##__ilayout *)						\
    ((char *)(obj) - offsetof(struct cls##__ilayout, chead)))
 
+/* --- @SOD__CAR@ --- *
+ *
+ * Arguments:	@...@ = a nonempty list of arguments
+ *
+ * Returns:	The first argument only.
+ */
+
+#if __STDC_VERSION__ >= 199901
+#  define SOD__CAR(...) SOD__CARx(__VA_LIST__, _)
+#  define SOD__CARx(a, ...) a
+#endif
+
 /*----- Utility macros ----------------------------------------------------*/
 
 /* --- @SOD_CLASSOF@ --- *
@@ -168,6 +180,19 @@ struct sod_chain {
 
 #define SOD_CONVERT(cls, obj) ((cls *)sod_convert(cls##__class, (obj)))
 
+/* --- @SOD_DECL@ --- *
+ *
+ * Arguments:	@cls_@ = a class type name
+ *		@var_@ = a variable name
+ *
+ * Use:		Declare @var_@ as a pointer to an initialized instance of
+ *		@cls_@ with automatic lifetime.
+ */
+
+#define SOD_DECL(cls_, var_)						\
+  struct cls_##__ilayout var_##__layout;				\
+  cls_ *var_ = cls_##__class->cls.init(&var_##__layout)
+
 /*----- Functions provided ------------------------------------------------*/
 
 /* --- @sod_subclassp@ --- *