From d90ad6d3cabb3c442b75c059630de2aae53e7143 Mon Sep 17 00:00:00 2001
From: Nicola Pero <nicola@gcc.gnu.org>
Date: Thu, 12 Sep 2002 17:29:26 +0000
Subject: [PATCH] Added long comments on why nil_method takes the arguments it
takes and how it's going to be used
From-SVN: r57073
---
libobjc/nil_method.c | 23 +++++++++++++++++++----
1 file changed, 19 insertions(+), 4 deletions(-)
diff --git a/libobjc/nil_method.c b/libobjc/nil_method.c
index 47201d69cc12..5e37c4d5dfb4 100644
--- a/libobjc/nil_method.c
+++ b/libobjc/nil_method.c
@@ -29,10 +29,25 @@ Boston, MA 02111-1307, USA. */
#include "runtime.h"
-/* nil_method is declared with variable arguments but the runtime calls it
- in a way that does not setup the variable arguments correctly. Some Architectures
- that have special arg calling conventions like x86-64 do need every function with
- variable arguments called the correct way. */
+/* When the receiver of a method invocation is nil, the runtime
+ returns nil_method() as the method implementation. This function
+ will be casted to whatever function was supposed to be executed to
+ execute that method (that function will take an id, followed by a
+ SEL, followed by who knows what arguments, depends on the method),
+ and executed.
+
+ For this reason, nil_method() should be a function which can be
+ called in place of any function taking an 'id' argument followed by
+ a 'SEL' argument, followed by zero, or one, or any number of
+ arguments (both a fixed number, or a variable number !).
+
+ There is no "proper" implementation of such a nil_method function
+ in C, however in all existing implementations it does not matter
+ when extra arguments are present, so we can simply create a function
+ taking a receiver and a selector, and all other arguments will be
+ ignored. :-)
+*/
+
id
nil_method (id receiver, SEL op __attribute__ ((__unused__)))
{
--
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