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In Smalltalk, there are 6 reserved keywords, or pseudo-variables:
thisContext. They are called pseudo-variables because they are predefined and cannot be assigned to.
nil are constants while the values of
thisContext vary dynamically as code is executed.
false are the unique instances of the
False. See Chapter 8 for more details.
self always refers to the receiver of the currently executing method.
super also refers to the receiver of the current method, but when you send a message to
super, the method-lookup changes so that it starts from the superclass of the class containing the method that uses
super. For further details see Chapter 5.
nil is the undefined object. It is the unique instance of the class
UndefinedObject. Instance variables, class variables and local variables are initialized to
thisContext is a pseudo-variable that represents the top frame of the run-time stack. In other words, it represents the currently executing
thisContext is normally not of interest to most programmers, but it is essential for implementing development tools like the debugger and it is also used to implement exception handling and continuations.