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1.199 UndefinedObject

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

1.199.1 UndefinedObject: basic  (instance)
1.199.2 UndefinedObject: class creation - alternative  (instance)
1.199.3 UndefinedObject: class polymorphism  (instance)
1.199.4 UndefinedObject: CObject interoperability  (instance)
1.199.5 UndefinedObject: dependents access  (instance)
1.199.6 UndefinedObject: printing  (instance)
1.199.7 UndefinedObject: still unclassified  (instance)
1.199.8 UndefinedObject: storing  (instance)
1.199.9 UndefinedObject: testing  (instance)


1.199.1 UndefinedObject: basic

copy
Answer the receiver.

deepCopy
Answer the receiver.

shallowCopy
Answer the receiver.


1.199.2 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

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

variableLongSubclass: 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


1.199.3 UndefinedObject: class polymorphism

allSubclasses
Return all the classes in the system.

instSize
Answer `0'.

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

methodDictionary
Answer `nil'.

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

subclass: classNameString
Define a subclass of the receiver with the given name. If the class is already defined, don't modify its instance or class variables but still, if necessary, recompile everything needed.

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.

variable: shape subclass: classNameString instanceVariableNames: stringInstVarNames classVariableNames: stringOfClassVarNames poolDictionaries: stringOfPoolNames category: categoryNameString
Define a variable subclass of the receiver with the given name, shape, instance variables, class variables, pool dictionaries and category. If the class is already defined, if necessary, recompile everything needed. The shape can be one of #byte #int8 #character #short #ushort #int #uint #int64 #uint64 #utf32 #float #double or #pointer.

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.


1.199.4 UndefinedObject: CObject interoperability

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

narrow
Return the receiver: a NULL pointer is always nil, whatever its type.


1.199.5 UndefinedObject: dependents access

addDependent: ignored
Fail, nil does not support dependents.

release
Ignore this call, nil does not support dependents.


1.199.6 UndefinedObject: printing

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

printOn: aStream in: aNamespace
Print on aStream a representation of the receiver as it would be accessed from aNamespace: nil is the same everywhere, so print the same as #printOn:


1.199.7 UndefinedObject: still unclassified


1.199.8 UndefinedObject: storing

isLiteralObject
Answer whether the receiver is expressible as a Smalltalk literal.

storeLiteralOn: aStream
Store on aStream some Smalltalk code which compiles to the receiver

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


1.199.9 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.

isNull
Answer whether the receiver represents a NULL C pointer. Always answer true.

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



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