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6.169 UndefinedObject

Defined in namespace Smalltalk
Category: Language-Implementation
I have the questionable distinction of being a class with only one instance, which is the object "nil".

6.169.1 UndefinedObject: class creation  (instance)
6.169.2 UndefinedObject: class creation - alternative  (instance)
6.169.3 UndefinedObject: CObject interoperability  (instance)
6.169.4 UndefinedObject: dependents access  (instance)
6.169.5 UndefinedObject: printing  (instance)
6.169.6 UndefinedObject: storing  (instance)
6.169.7 UndefinedObject: testing  (instance)


6.169.1 UndefinedObject: class creation

metaclassFor: classNameString
Create a Metaclass object for the given class name. The metaclass is a subclass of Class

removeSubclass: aClass
Ignored -- necessary to support disjoint class hierarchies

subclass: classNameString
instanceVariableNames: stringInstVarNames classVariableNames: stringOfClassVarNames poolDictionaries: stringOfPoolNames category: categoryNameString Define a fixed subclass of the receiver with the given name, instance variables, class variables, pool dictionaries and category. If the class is already defined, if necessary, recompile everything needed.

variableByteSubclass: classNameString
instanceVariableNames: stringInstVarNames classVariableNames: stringOfClassVarNames poolDictionaries: stringOfPoolNames category: categoryNameString Define a byte variable subclass of the receiver with the given name, instance variables, class variables, pool dictionaries and category. If the class is already defined, if necessary, recompile everything needed.

variableSubclass: classNameString
instanceVariableNames: stringInstVarNames classVariableNames: stringOfClassVarNames poolDictionaries: stringOfPoolNames category: categoryNameString Define a variable pointer subclass of the receiver with the given name, instance variables, class variables, pool dictionaries and category. If the class is already defined, if necessary, recompile everything needed.

variableWordSubclass: classNameString
instanceVariableNames: stringInstVarNames classVariableNames: stringOfClassVarNames poolDictionaries: stringOfPoolNames category: categoryNameString Define a word variable subclass of the receiver with the given name, instance variables, class variables, pool dictionaries and category. If the class is already defined, if necessary, recompile everything needed.


6.169.2 UndefinedObject: class creation - alternative

subclass: classNameString classInstanceVariableNames: stringClassInstVarNames instanceVariableNames: stringInstVarNames classVariableNames: stringOfClassVarNames poolDictionaries: stringOfPoolNames
Don't use this, it is only present to file in from IBM Smalltalk

subclass: classNameString instanceVariableNames: stringInstVarNames classVariableNames: stringOfClassVarNames poolDictionaries: stringOfPoolNames
Don't use this, it is only present to file in from IBM Smalltalk

variableByteSubclass: classNameString classInstanceVariableNames: stringClassInstVarNames instanceVariableNames: stringInstVarNames classVariableNames: stringOfClassVarNames poolDictionaries: stringOfPoolNames
Don't use this, it is only present to file in from IBM Smalltalk

variableByteSubclass: classNameString instanceVariableNames: stringInstVarNames classVariableNames: stringOfClassVarNames poolDictionaries: stringOfPoolNames
Don't use this, it is only present to file in from IBM Smalltalk

variableSubclass: classNameString classInstanceVariableNames: stringClassInstVarNames instanceVariableNames: stringInstVarNames classVariableNames: stringOfClassVarNames poolDictionaries: stringOfPoolNames
Don't use this, it is only present to file in from IBM Smalltalk

variableSubclass: classNameString instanceVariableNames: stringInstVarNames classVariableNames: stringOfClassVarNames poolDictionaries: stringOfPoolNames
Don't use this, it is only present to file in from IBM Smalltalk

variableWordSubclass: classNameString classInstanceVariableNames: stringClassInstVarNames instanceVariableNames: stringInstVarNames classVariableNames: stringOfClassVarNames poolDictionaries: stringOfPoolNames
Don't use this, it is only present to file in from IBM Smalltalk

variableWordSubclass: classNameString instanceVariableNames: stringInstVarNames classVariableNames: stringOfClassVarNames poolDictionaries: stringOfPoolNames
Don't use this, it is only present to file in from IBM Smalltalk


6.169.3 UndefinedObject: CObject interoperability

free
Do nothing, a NULL pointer can be safely freed.


6.169.4 UndefinedObject: dependents access

addDependent: ignored
Refer to the comment in Object|dependents.

release
Nil release is a no-op


6.169.5 UndefinedObject: printing

printOn: aStream
Print a representation of the receiver on aStream.


6.169.6 UndefinedObject: storing

storeOn: aStream
Store Smalltalk code compiling to the receiver on aStream.


6.169.7 UndefinedObject: testing

ifNil: nilBlock
Evaluate nilBlock if the receiver is nil, else answer nil

ifNil: nilBlock ifNotNil: notNilBlock
Evaluate nilBlock if the receiver is nil, else evaluate notNilBlock, passing the receiver.

ifNotNil: notNilBlock
Evaluate notNilBlock if the receiver is not nil, passing the receiver. Else answer nil

ifNotNil: notNilBlock ifNil: nilBlock
Evaluate nilBlock if the receiver is nil, else evaluate notNilBlock, passing the receiver.

isNil
Answer whether the receiver is the undefined object nil. Always answer true.

notNil
Answer whether the receiver is not the undefined object nil. Always answer false.




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