>>>>> "Madhu" == Madhu <[EMAIL PROTECTED]> writes:
Madhu> * Raymond Toy <[EMAIL PROTECTED]> :
Madhu> Wrote on Tue, 02 Dec 2008 20:23:45 -0500:
Madhu> |> It may also have been a tradeoff, [since it is not being done in
the
Madhu> |> compiler] and you want to have at least one path available to the
Madhu> |> programmer to set a slot value that avoids overhead of a type
check.
Madhu> |
Madhu> | I've implemented this already. It basically does a check-type for
(setf
Madhu> | slot-value) for standard objects. This doesn't change what
happens when
Madhu> | slot-value is used in a method.
Madhu> I'm not sure this is a good idea. (But I have not measured the cost
of
Madhu> the change, NOTE: I'm not objecting to the change)
I did a quick test with:
(defclass foo2 ()
((slot :type single-float :initform 1.2f0)
(slot2)))
(defclass bar ()
((a :type fixnum :initform 0)))
(defparameter *o* (make-instance 'foo2))
(defmethod setslot ((obj bar) val)
(setf (slot-value *o* 'slot) val)
(setf (slot-value obj 'a) val))
Compile up the previous code. Then (setf (slot-value (make-instance
'foo2) 'slot) "string") signals an error.
But (setslot (make-instance 'bar) 99) doesn't signal an error even
though we're assigning a fixnum to a slot of type single-float.
Hence, the change I made doesn't apply to slot-value in methods. (I
guess slot-value in methods takes a different path.)
I don't know PCL well enough to know exactly how methods get called or
which ones are run.
Ray
