[Newbies] binary message ==

Torsten Bergmann astares at gmx.de
Fri Oct 31 08:11:04 UTC 2008

>I've never seen == in Smalltalk before.

=	The objects are equal
==	The object(s) are identical

If obj1 == obj2 results in true means they represent the same instance.

>It doesn't seem to be a method in Object within Squeak. What's going on here?

It's defined in ProtoObject (the superclass of Object) which is the root class in the
Squeak hierarchy. Other Smalltalks have Object as the root class of the hierarchy.
You wont find the implemention of #== interesting since it is implemented as a primitive.

However you should learn about the difference of = and ==. I'm sure it is explained in
any Smalltalk book [1].

BTW: Just click on "open" -> "method finder", enter "==" and ENTER. Click on the first displayed
         result. The Method finder will show you where a specific method is implemented.
         This tool has some more nice features: see http://wiki.squeak.org/squeak/1916


[1] http://stephane.ducasse.free.fr/FreeBooks.html

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