Index: doc/next-tutorial.html =================================================================== diff -u -r56136cbbc9bd838be349205d7a7718bbdddb9f9f -r25c826ca05bc7c8e459d273b8990fe9c42505a86 --- doc/next-tutorial.html (.../next-tutorial.html) (revision 56136cbbc9bd838be349205d7a7718bbdddb9f9f) +++ doc/next-tutorial.html (.../next-tutorial.html) (revision 25c826ca05bc7c8e459d273b8990fe9c42505a86) @@ -1068,7 +1068,7 @@

  • As in the example above, we use :variable to define the - instance variable things for this object (the object stack). + instance variable things for this object (the object stack).

    • @@ -1463,7 +1463,7 @@ 24 
    nx::Class create Stack2 {
 
-    :public class method available_stacks {} {
+   :public class method available_stacks {} {
       return [llength [:info instances]]
    }
 
@@ -1665,7 +1665,7 @@
 parameters are optional (they can be left out). By using parameter
 options, we can as well define positional parameters, which are
 optional, and non-positional parameters, which are required.
    
-
    Listing 17: Optional and Required Parameters
    
+
    Listing 17: Optional and Required Method Parameters
    
 
    
 
    
+
      1
+  2
+  3
+  4
+  5
+  6
+  7
+  8
+  9
+ 10
+ 11
+
    Class create C {
+
+  :method foo args {...}
+    # Method scoped variable a
+    set a 1
+    # Instance variable b
+    set :b 2
+    # Global variable/namespaced variable c
+    set ::c 3
+  }
+}
    
+
    Listing 28 shows a method foo
+of some class C referring to differently scoped variables.
    
+
    So, in general, there is no need to define or declare instance
+variables in NX. However, in some cases, a definition is useful. For
+example, one can define properties on classes, which are inherited to
+subclasses, and which are used during object initialization.  As shown
+in the example class Student, properties can have defaults, which
+are used as well during initialization.
    
+
    In short, a property is an instance variable with accessors, where
+the property definition might carry as well value-constraints and a
+default value.
    
+
    In some cases one would like to define instance variables without
+accessors, e.g. for keeping the internal state of an object.  For this
+purpose, one can use the predefined method variable, which is in
+many respects similar to property. One difference is, that
+property uses the same syntax as for method parameters, and
+variable receives the default value as a separate argument (similar
+to the variable command in Tcl. The introductory Stack example in in
+Listing 2 used already the method
+variable.
    
+
    Listing 29: Declaring Variables
    
+
    
+
    
+
      1
+  2
+  3
+  4
+  5
+  6
+  7
+  8
+  9
+ 10
+ 11
+ 12
+ 13
+ 14
+ 15
+
    Class create Base {
+  :variable x 1
+  # ...
+}
+
+Class create Derived -superclass Base {
+  :variable y 2
+  # ...
+}
+
+# Create instance of the class Derived
+Derived create d1
+
+# Object d1 has instance variables
+# x == 1 and y == 2
    
+
    Note that the variable definitions are inherited in the same way as
+properties. The example in Listing 29 shows a
+class Derived that inherits from Base. When an instance d1 is
+created, it will contain the two instance variables x and y.
    
+
    Listing 30: Setting Variables in the Constructor
    
+
    
+
    
+
      1
+  2
+  3
+  4
+  5
+  6
+  7
+  8
+  9
+ 10
+ 11
+ 12
+ 13
+ 14
+ 15
+ 16
+ 17
+ 18
+ 19
+
    Class create Base2 {
+ # ...
+ :method init {} {
+   set :x 1
+   # ....
+ }
+}
+
+Class create Derived2 -superclass Base2 {
+ # ...
+ :method init {} {
+   set :y 2
+   next
+   # ....
+ }
+}
+
+# Create instance of the class Derived2
+Derived2 create d2
    
+
    In many other object oriented languages, the instance variables are
+initialized by the constructor, similar to class Derived2 in
+Listing 30 . This approach is certainly
+as well possible in NX. Note however, that the approach using
+constructors requires an explicit method chaining between the
+constructors and is less declarative.
    
+
+
    
+
    3.2.4. Additional Parameter Types for Object Parameters
    
 
    More detailed definition of the object parameter types comes here.
    
 
    
 
    
-
    3.2.4. Slot Classes and Slot Objects
    
+
    3.2.5. Slot Classes and Slot Objects
    
 
    In one of the previous sections, we defined scripted (application
 defined) checker methods on a class named nx::Slot.  In general NX
 offers the possibility to define value checkers not only for all
@@ -2450,12 +2640,12 @@
 
    
 slots.png
 
    
-
    Figure 28. Slot Classes and Objects
    
+
    Figure 31. Slot Classes and Objects
    
 
    
 
    
 
    
 
    
-
    3.2.5. Attribute Slots
    
+
    3.2.6. Attribute Slots
    
 
    Still Missing
    
 
      
 
    • 
@@ -2494,10 +2684,15 @@
 
    
 
    
 
    
-
    4. Miscellaneous
    
+
    4. Method Protection
    
 
    
+
    
+
    
+
    
+
    5. Miscellaneous
    
+
    
 
    
-
    4.1. Unknown Handlers
    
+
    5.1. Unknown Handlers
    
 
    NX provides two kinds of unknown handlers:
    
 
      
 
    • 
@@ -2512,12 +2707,12 @@
 
      • 
 
    
 
    
-
    4.1.1. Unknown Handlers for Methods
    
+
    5.1.1. Unknown Handlers for Methods
    
 
    Object and classes might be equipped
 with a method unknown which is called in cases, where an unknown
 method is called. The method unknown receives as first argument the
 called method followed by the provided arguments
    
-
    Listing 29: Unknown Method Handler
    
+
    Listing 32: Unknown Method Handler