On 29 Aug 2003, Martin Drautzburg wrote:
> I thought I knew it all, but ...
>
> I created the following class
>
>         Object subclass: #Foo ...
>         bar
>                 ^ self
>
> When I create aFoo and inspect it, it answers true to both
>         self respondsTo: #bar and
>         super respondsTo: #bar
"self" and "super" both refer to the receiver (so both refer to the
_same object_).  Since the receiver responds to #bar, both of these
anwser correctly.  The only difference between "self" and "super" is
_where_ the method _lookup_ begins.  (Sends to self are lookuped up
starting in the class of the receiver -- even if that's below the
method that's doing the send because of inheritance; sends to super
are looked up starting in the _superclass_ of the class in which the
_method_ [the one in which the send to super is being performed] is
_defined_, regardless of the actual class of the receiver.)
It might help to add this method to the instance side of Foo
 respondsTo: aSelector
  ^42
and then try the "inspector experiment" again.  After 2 seconds'
thought, it'll "click".
> also I get Foo no matter if I ask
>         self class or
>         super class
>
> Can someone explain ?
"self" and "super" are the same object.
> The reason why I was doing this, was in a #mouseDown method I thoght
> I'd invoke mouseDown on super if it came from a mouse button I didn't
> handle. But since I didn't know if the superclass has a #mouseDown
> method at all I tried to figure that out by sending a #respondsTo:
If you know your superclass then you can just send it "canUnderstand:
aSymbol" directly.
    Foo canUnderstand: #bar    => true
    Object canUnderstand: #bar => false
Hint: select the text "respondsTo:" and browse its implementors
(Command-M).
Ian