Add mechanism for gdl2.

git-svn-id: svn+ssh://svn.gna.org/svn/gnustep/libs/base/trunk@29866 72102866-910b-0410-8b05-ffd578937521

ChangeLog

@@ -1,3 +1,11 @@
+2010-03-07 Richard Frith-Macdonald <rfm@gnu.org>
+
+	* Source/Additions/GSObjCRuntime.m:
+	* Headers/Additions/GNUstepBase/GSObjCRuntime.h:
+	Add function to add 'overrides' as a form of programmatically
+	controlled category similar to behaviors, giving an app control
+	over the order in which methods are added to a class.
+
 2010-03-05 Richard Frith-Macdonald <rfm@gnu.org>
 
 	* Source/Additions/GSCompatibility.h:

Headers/Additions/GNUstepBase/GSObjCRuntime.h

@@ -116,9 +116,66 @@ GSObjCMethodNames(id obj, BOOL recurse);
 GS_EXPORT NSArray *
 GSObjCVariableNames(id obj, BOOL recurse);
 
+/**
+ * <p>A Behavior can be seen as a "Protocol with an implementation" or a
+ * "Class without any instance variables".  A key feature of behaviors
+ * is that they give a degree of multiple inheritance.
+ * </p>
+ * <p>Behavior methods, when added to a class, override the class's
+ * superclass methods, but not the class's methods.
+ * </p>
+ * <p>Whan a behavior class is added to a receiver class, not only are the
+ * methods defined in the behavior class added, but the methods from the
+ * behavior's class hierarchy are also added (unless already present).
+ * </p>
+ * <p>It's not the case that a class adding behaviors from another class
+ * must have "no instance vars".  The receiver class just has to have the
+ * same layout as the behavior class (optionally with some additional
+ * ivars after those of the behavior class).
+ * </p>
+ * <p>This function provides Behaviors without adding any new syntax to
+ * the Objective C language.  Simply define a class with the methods you
+ * want to add, then call this function with that class as the behavior
+ * argument.
+ * </p>
+ * <p>This function should be called in the +initialize method of the receiver.
+ * </p>
+ * <p>If you add several behaviors to a class, be aware that the order of
+ * the additions is significant.
+ * </p>
+ */
 GS_EXPORT void
 GSObjCAddClassBehavior(Class receiver, Class behavior);
 
+/**
+ * <p>An Override can be seen as a "category implemented as a separate class
+ * and manually added to the receiver class under program control, rather
+ * than automatically added by the compiler/runtime.
+ * </p>
+ * <p>Override methods, when added to a receiver class, replace the class's
+ * class's methods of the same name (or are added if the class did not define
+ * methods with that name).
+ * </p>
+ * <p>It's not the case that a class adding overrides from another class
+ * must have "no instance vars".  The receiver class just has to have the
+ * same layout as the override class (optionally with some additional
+ * ivars after those of the override class).
+ * </p>
+ * <p>This function provides overrides without adding any new syntax to
+ * the Objective C language.  Simply define a class with the methods you
+ * want to add, then call this function with that class as the override
+ * argument.
+ * </p>
+ * <p>This function should usually be called in the +initialize method
+ * of the receiver.
+ * </p>
+ * <p>If you add several overrides to a class, be aware that the order of
+ * the additions is significant.
+ * </p>
+ */
+GS_EXPORT void
+GSObjCAddClassOverride(Class receiver, Class override);
+
 GS_EXPORT NSValue *
 GSObjCMakeClass(NSString *name, NSString *superName, NSDictionary *iVars);
 

Source/Additions/GSObjCRuntime.m

@@ -757,30 +757,6 @@ GSProtocolFromName(const char *name)
 }
 
 
-/**
- * <p>A Behavior can be seen as a "Protocol with an implementation" or a
- * "Class without any instance variables".  A key feature of behaviors
- * is that they give a degree of multiple inheritance.
- * </p>
- * <p>Behavior methods, when added to a class, override the class's
- * superclass methods, but not the class's methods.
- * </p>
- * <p>It's not the case that a class adding behaviors from another class
- * must have "no instance vars".  The receiver class just has to have the
- * same layout as the behavior class (optionally with some additional
- * ivars after those of the behavior class).
- * </p>
- * <p>This function provides Behaviors without adding any new syntax to
- * the Objective C language.  Simply define a class with the methods you
- * want to add, then call this function with that class as the behavior
- * argument.
- * </p>
- * <p>This function should be called in the +initialize method of the receiver.
- * </p>
- * <p>If you add several behaviors to a class, be aware that the order of
- * the additions is significant.
- * </p>
- */
 void
 GSObjCAddClassBehavior(Class receiver, Class behavior)
 {
@@ -853,6 +829,55 @@ GSObjCAddClassBehavior(Class receiver, Class behavior)
   GSFlushMethodCacheForClass (receiver);
 }
 
+void
+GSObjCAddClassOverride(Class receiver, Class override)
+{
+  unsigned int	count;
+  Method	*methods;
+
+  if (YES == class_isMetaClass(receiver))
+    {
+      fprintf(stderr, "Trying to add override (%s) to meta class (%s)\n",
+	class_getName(override), class_getName(receiver));
+      abort();
+    }
+  if (YES == class_isMetaClass(override))
+    {
+      fprintf(stderr, "Trying to add meta class as override (%s) to (%s)\n",
+	class_getName(override), class_getName(receiver));
+      abort();
+    }
+  if (class_getInstanceSize(receiver) < class_getInstanceSize(override))
+    {
+      fprintf(stderr, "Trying to add override (%s) with instance "
+	"size larger than class (%s)\n",
+	class_getName(override), class_getName(receiver));
+      abort();
+    }
+
+  BDBGPrintf("Adding override to class %s\n", class_getName(receiver));
+  BDBGPrintf("  instance methods from %s\n", class_getName(override));
+
+  /* Add instance methods */
+  methods = class_copyMethodList(override, &count);
+  if (methods != NULL)
+    {
+      GSObjCAddMethods (receiver, methods, YES);
+      free(methods);
+    }
+
+  /* Add class methods */
+  BDBGPrintf("Adding class methods from %s\n",
+    class_getName(object_getClass(override)));
+  methods = class_copyMethodList(object_getClass(override), &count);
+  if (methods != NULL)
+    {
+      GSObjCAddMethods (object_getClass(receiver), methods, YES);
+      free(methods);
+    }
+  GSFlushMethodCacheForClass (receiver);
+}
+