On 13 Apr 2009, at 21:06, Thomas Kupper wrote:
On the other hand, if there are only three calls to objc_msgSend in
only one file I could maybe just replace these three calls. But the
objc_msg_lookup calls seems to be quite unusal.
With "quite unsual" I mean how can I pass the va_list since the
objc_msg_lookup only takes two arguments.
You are only passing two arguments to objc_msg_forward(). You are
passing all of the arguments provided to the macro to the function
returned by objc_msg_forward(). The __VA_ARGS__ macro is not a
va_list, it is a special C99 preprocessor token which is exapended to
the arguments passed to the variadic macro.
This call:
objc_msgSend(obj, sel, arg, arg2);
Will, with the macro I gave you, expand to:
objc_msg_lookup(obj, sel)(obj, sel, arg, arg2);
There are some corner cases where this won't work (i.e. if obj or sel
is an expression, it will be expanded multiple times - ideally you
need to assign these to a temporary variable first, but for most cases
the version I gave you should be adequate).
David
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