Merge pull request steipete#16 from steipete/typed-arguments

Typed arguments

Aspects.h

@@ -16,35 +16,53 @@ typedef NS_OPTIONS(NSUInteger, AspectOptions) {
 };
 
 /// Opaque Aspect Token that allows to deregister the hook.
-@protocol Aspect <NSObject>
+@protocol AspectToken <NSObject>
 
 /// Deregisters an aspect.
 /// @return YES if deregistration is successful, otherwise NO.
 - (BOOL)remove;
 
 @end
 
+/// The AspectInfo protocol is the first parameter of our block syntax.
+@protocol AspectInfo <NSObject>
+
+/// The instance that is currently hooked.
+- (id)instance;
+
+/// The original invocation of the hooked method.
+- (NSInvocation *)originalInvocation;
+
+/// All method arguments, boxed. This is lazily evaluated.
+- (NSArray *)arguments;
+
+@end
+
 /**
  Aspects uses Objective-C message forwarding to hook into messages. This will create some overhead. Don't add aspects to methods that are called a lot. Aspects is meant for view/controller code that is not called a 1000 times per second.
 
- Aspects collects all arguments in the `arguments` array. Primitive values will be boxed.
  Adding aspects returns an opaque token which can be used to deregister again. All calls are thread safe.
  */
 @interface NSObject (Aspects)
 
 /// Adds a block of code before/instead/after the current `selector` for a specific class.
-/// If you choose `AspectPositionInstead`, the `arguments` array will contain the original invocation as last argument.
+///
+/// @param block Aspects replicates the type signature of the method being hooked.
+/// The first parameter will be `id<AspectInfo>`, followed by all parameters of the method.
+/// These parameters are optional and will be filled to match the block signature.
+/// You can even use an empty block, or one that simple gets `id<AspectInfo>`.
+///
 /// @note Hooking static methods is not supported.
 /// @return A token which allows to later deregister the aspect.
-+ (id<Aspect>)aspect_hookSelector:(SEL)selector
++ (id<AspectToken>)aspect_hookSelector:(SEL)selector
                       withOptions:(AspectOptions)options
-                       usingBlock:(void (^)(id instance, NSArray *args))block
+                       usingBlock:(id)block
                             error:(NSError **)error;
 
 /// Adds a block of code before/instead/after the current `selector` for a specific instance.
-- (id<Aspect>)aspect_hookSelector:(SEL)selector
+- (id<AspectToken>)aspect_hookSelector:(SEL)selector
                       withOptions:(AspectOptions)options
-                       usingBlock:(void (^)(id instance, NSArray *args))block
+                       usingBlock:(id)block
                             error:(NSError **)error;
 
 @end
@@ -56,6 +74,9 @@ typedef NS_ENUM(NSUInteger, AspectsErrorCode) {
     AspectsErrorSelectorDeallocPosition,               /// When hooking dealloc, only AspectPositionBefore is allowed.
     AspectsErrorSelectorAlreadyHookedInClassHierarchy, /// Statically hooking the same method in subclasses is not allowed.
     AspectsErrorFailedToAllocateClassPair,             /// The runtime failed creating a class pair.
+    AspectsErrorMissingBlockSignature,                 /// The block misses compile time signature info and can't be called.
+    AspectsErrorIncompatibleBlockSignature,            /// The block signature does not match the method or is too large.
+
     AspectsErrorRemoveObjectAlreadyDeallocated = 100   /// (for removing) The object hooked is already deallocated.
 };