User's Guide
Some objects in the system are implemented and interpreted specially by the
virtual machine and by the Swapper for performance and cross-load
encoding. The restrictions on special objects are as follows:
- Character
- Instances of Character should be obtained only through
constants or as the result of normal system messages and computations.
Instances of Character must not be created through the
basicNew operation. The Swapper makes the assumption that
the ASCII (or EBCDIC) value of Character is always valid.
- False
- Instances of False should not be created. The Swapper
makes the assumption that there is only one instance of False and
that instance is the special object false.
- SmallInteger
- Instances of SmallInteger should be created only through
constants or as the result of normal system messages and computations.
Instances of SmallInteger must not be created through the
basicNew operation.
- True
- Instances of True should not be created. The Swapper
makes the assumption that there is only one instance of True and
that instance is the special object true.
- UndefinedObject
- Instances of UndefinedObject should not be created. The
Swapper makes the assumption that there is only one instance of
UndefinedObject and that instance is the special object
nil.
Violation of these restrictions may cause unpredictable results.
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