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authorClaus Gittinger <cg@exept.de>
Fri, 26 Apr 1996 09:12:36 +0200
changeset 1303 8fdc2c653d13
parent 1302 b39a598b0937
child 1304 60d726d6d526
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False.st file | annotate | diff | comparison | revisions
True.st file | annotate | diff | comparison | revisions
UndefObj.st file | annotate | diff | comparison | revisions
UndefinedObject.st file | annotate | diff | comparison | revisions 
--- a/False.st	Thu Apr 25 20:29:09 1996 +0200
+++ b/False.st	Fri Apr 26 09:12:36 1996 +0200
@@ -46,6 +46,9 @@
     (redefining ifTrue: to something else will probably crash the smalltalk
      world anyway ...)
 
+    [see also:]
+        True
+
     [author:]
         Claus Gittinger
 "
@@ -155,4 +158,4 @@
 !False class methodsFor:'documentation'!
 
 version
-^ '$Header: /cvs/stx/stx/libbasic/False.st,v 1.16 1996-04-25 16:51:48 cg Exp $'! !
+^ '$Header: /cvs/stx/stx/libbasic/False.st,v 1.17 1996-04-26 07:11:48 cg Exp $'! !
--- a/True.st	Thu Apr 25 20:29:09 1996 +0200
+++ b/True.st	Fri Apr 26 09:12:36 1996 +0200
@@ -46,6 +46,9 @@
     (redefining ifTrue: to something else will probably crash the smalltalk
      world anyway ...)
 
+    [see also:]
+        False
+        
     [author:]
         Claus Gittinger
 "
@@ -155,5 +158,5 @@
 !True class methodsFor:'documentation'!
 
 version
-    ^ '$Header: /cvs/stx/stx/libbasic/True.st,v 1.17 1996-04-25 16:51:53 cg Exp $'
+    ^ '$Header: /cvs/stx/stx/libbasic/True.st,v 1.18 1996-04-26 07:12:22 cg Exp $'
 ! !
--- a/UndefObj.st	Thu Apr 25 20:29:09 1996 +0200
+++ b/UndefObj.st	Fri Apr 26 09:12:36 1996 +0200
@@ -35,16 +35,26 @@
 
 documentation
 "
-    there is only one instance of this class: nil, representing an undefined
-    or otherwise unspecified object.
+    there is only one instance of this class: nil, 
+    representing an undefined or otherwise unspecified object.
 
     All instance variables, array elements and even method/block local 
     variables are initially set to nil.
-    Since in Smalltalk/X, nil is represented by a special pointer value,
+
+    Since in Smalltalk/X, nil is represented by a special pointer value (NULL),
     there can be only one instance of UndefinedObject, and no subclassing is
     possible. 
-    (to be exact: subclassing is technically possible, but instances of it 
-     would not be recognized as being nil - therefore, subclassing is blocked)
+    (to be exact: subclassing UndefinedObject is technically possible, 
+     but instances of it would not be recognized as being nil 
+     - therefore, subclassing is blocked and an error is raised when it is tried)
+
+    For advanced users:
+      Beside the above role, nil can be subclassed (!!).
+      This creates a class which inherits no protocol whatsoever - not even
+      the basic interfaces as defined by the Object class. Subclasses of nil
+      are useful if all messages send to instances should trap into the
+      #doesNotUnderstand: method. For example, proxy objects are typically defined
+      this way.
 
     [author:]
         Claus Gittinger
@@ -286,5 +296,5 @@
 !UndefinedObject class methodsFor:'documentation'!
 
 version
-    ^ '$Header: /cvs/stx/stx/libbasic/Attic/UndefObj.st,v 1.22 1996-04-25 16:53:16 cg Exp $'
+    ^ '$Header: /cvs/stx/stx/libbasic/Attic/UndefObj.st,v 1.23 1996-04-26 07:12:36 cg Exp $'
 ! !
--- a/UndefinedObject.st	Thu Apr 25 20:29:09 1996 +0200
+++ b/UndefinedObject.st	Fri Apr 26 09:12:36 1996 +0200
@@ -35,16 +35,26 @@
 
 documentation
 "
-    there is only one instance of this class: nil, representing an undefined
-    or otherwise unspecified object.
+    there is only one instance of this class: nil, 
+    representing an undefined or otherwise unspecified object.
 
     All instance variables, array elements and even method/block local 
     variables are initially set to nil.
-    Since in Smalltalk/X, nil is represented by a special pointer value,
+
+    Since in Smalltalk/X, nil is represented by a special pointer value (NULL),
     there can be only one instance of UndefinedObject, and no subclassing is
     possible. 
-    (to be exact: subclassing is technically possible, but instances of it 
-     would not be recognized as being nil - therefore, subclassing is blocked)
+    (to be exact: subclassing UndefinedObject is technically possible, 
+     but instances of it would not be recognized as being nil 
+     - therefore, subclassing is blocked and an error is raised when it is tried)
+
+    For advanced users:
+      Beside the above role, nil can be subclassed (!!).
+      This creates a class which inherits no protocol whatsoever - not even
+      the basic interfaces as defined by the Object class. Subclasses of nil
+      are useful if all messages send to instances should trap into the
+      #doesNotUnderstand: method. For example, proxy objects are typically defined
+      this way.
 
     [author:]
         Claus Gittinger
@@ -286,5 +296,5 @@
 !UndefinedObject class methodsFor:'documentation'!
 
 version
-    ^ '$Header: /cvs/stx/stx/libbasic/UndefinedObject.st,v 1.22 1996-04-25 16:53:16 cg Exp $'
+    ^ '$Header: /cvs/stx/stx/libbasic/UndefinedObject.st,v 1.23 1996-04-26 07:12:36 cg Exp $'
 ! !
hg/stx-libbasic