1.201.10 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.