Varargs type stringification (#50972)

[Owen Taylor <otaylor redhat com>]

g_strdup_value_contents() is neat, but not all that convenient to 
use since:

 - You have to construct a value if you don't 
 - You have to free the results

Here's a patch to add:

gchar*                g_strdup_type             (GType         type,
					         ...);
G_CONST_RETURN char * g_stringify_type          (GType         type,
					         ...);

Which do the same thing but with GType + varargs. g_stringfy_type()
uses a small ring buffer of static results to make it real easy
to use in debug printfs.

Regards,
                                        Owen

Index: gvaluetypes.c
===================================================================
RCS file: /cvs/gnome/glib/gobject/gvaluetypes.c,v
retrieving revision 1.11
diff -u -r1.11 gvaluetypes.c
--- gvaluetypes.c	2001/03/18 04:44:38	1.11
+++ gvaluetypes.c	2001/03/27 16:47:17
@@ -779,3 +779,90 @@
 
   return contents;
 }
+
+static gchar*
+g_strdup_type_valist (GType   type,
+		      va_list var_args)
+{
+  GValue tmp_value = { 0 };
+  gchar *error = NULL;
+  gchar *value;
+
+  g_value_init (&tmp_value, type);
+
+  G_VALUE_COLLECT (&tmp_value, var_args, 0, &error);
+
+  if (error)
+    {
+      /* we deliberately leak the value here, it might not be
+       * in a sane state if an error condition occoured
+       */
+      g_free (error);
+      value = g_strdup ("???");
+    }
+  else
+    {
+      value = g_strdup_value_contents (&tmp_value);
+      g_value_unset (&tmp_value);
+    }
+
+  return value;
+}
+
+/**
+ * g_strdup_type:
+ * @type: a #GType
+ * 
+ * Produce a string representation of the first argument in the
+ * variable argument list, which is of type @type.
+ * 
+ * Return value: a string representation of the type. Free with g_free().
+ **/
+gchar*
+g_strdup_type (GType type, ...)
+{
+  gchar *result;
+  va_list var_args;
+
+  va_start (var_args, type);
+  result = g_strdup_type_valist (type, var_args);
+  va_end (var_args);
+
+  return result;
+}
+
+#define N_DEBUG_STRINGS 16
+
+/**
+ * g_stringify_type:
+ * @type: a #GType
+ * 
+ * Like g_strdup_type() but the result is a pointer to a static
+ * buffer and doesn't need to be freed. This function is not
+ * thread safe. The static buffers will be recycled after some
+ * number of calls to this function (currently 16.)
+ * 
+ * Return value: a string representation of the type. Should
+ *               not be freed.
+ **/
+G_CONST_RETURN char *
+g_stringify_type (GType type, ...)
+{
+  static char *debug_strings[N_DEBUG_STRINGS];
+  static int debug_index = 0;
+
+  G_CONST_RETURN char *result;
+  va_list var_args;
+  
+  g_free (debug_strings[debug_index]);
+
+  va_start (var_args, type);
+  result = debug_strings[debug_index] = g_strdup_type_valist (type, var_args);
+  va_end (var_args);
+
+  debug_index = (debug_index + 1) % N_DEBUG_STRINGS;
+
+  return result;
+}
+
+
Index: gvaluetypes.h
===================================================================
RCS file: /cvs/gnome/glib/gobject/gvaluetypes.h,v
retrieving revision 1.10
diff -u -r1.10 gvaluetypes.h
--- gvaluetypes.h	2001/03/18 04:44:38	1.10
+++ gvaluetypes.h	2001/03/27 16:47:17
@@ -79,9 +79,12 @@
 gpointer	      g_value_get_pointer	(const GValue *value);
 
 
-/* debugging aid, describe value contents as string */
+/* debugging aid, describe type/value contents as string */
 gchar*                g_strdup_value_contents   (const GValue *value);
-
+gchar*                g_strdup_type             (GType         type,
+					         ...);
+G_CONST_RETURN char * g_stringify_type          (GType         type,
+					         ...);
 
 /* --- marshaller specific --- */
 void g_value_set_string_take_ownership		(GValue		   *value,
Index: testgruntime.c
===================================================================
RCS file: /cvs/gnome/glib/gobject/testgruntime.c,v
retrieving revision 1.1
diff -u -r1.1 testgruntime.c
--- testgruntime.c	2001/03/09 14:02:30	1.1
+++ testgruntime.c	2001/03/27 16:47:17
@@ -155,8 +155,22 @@
   return test_object_type;
 }
 
+void
+test_type_stringify (void)
+{
+  TestObject *tobject; 
 
+  g_print ("\nTesting stringification...\n");
+  g_print ("int - %s\n", g_stringify_type (G_TYPE_INT, 5));
+  g_print ("double - %s\n", g_stringify_type (G_TYPE_DOUBLE, 5.0));
+  tobject = g_object_new (TEST_TYPE_OBJECT, NULL);
+  g_print ("object - %s\n", g_stringify_type (TEST_TYPE_OBJECT, tobject));
+  g_print ("object (generic) - %s\n", g_stringify_type (G_TYPE_OBJECT, tobject));
+  g_print ("done testing stringification...\n\n");
 
+  g_object_unref (tobject);
+}
+
 int
 main (int   argc,
       char *argv[])
@@ -178,6 +192,8 @@
   g_object_unref (sigarg);
   g_object_unref (tobject);
 
+  test_type_stringify();
+  
   g_message ("%s done", argv[0]);
 
   return 0;