" Smalltalk/UndefinedObject.st -- nil						-*- Smalltalk -*- "

UndefinedObject : Object ()

[UndefinedObject _beNilType]

UndefinedObject isNil	[ ^true ]
UndefinedObject notNil	[ ^false ]

UndefinedObject not
[
    ^true
]

UndefinedObject ifTrue: aBlock [ ^nil ]
UndefinedObject and:    aBlock [ ^nil ]

UndefinedObject ifFalse: aBlock [ ^aBlock value ]
UndefinedObject or:      aBlock [ ^aBlock value ]

UndefinedObject assert
[
    self error: 'assertion failed'
]

UndefinedObject refute []