documented object constrs; endb works again

doc/tut2.txt

@@ -46,8 +46,7 @@ Objects
 Like tuples, objects are a means to pack different values together in a
 structured way. However, objects provide many features that tuples do not:
 They provide inheritance and information hiding. Because objects encapsulate
-data, the ``()`` tuple constructor cannot be used to construct objects. So
-the order of the object's fields is not as important as it is for tuples. The
+data, the ``T()`` object constructor should only be used internally and the
 programmer should provide a proc to initialize the object (this is called
 a *constructor*).
 
@@ -55,7 +54,6 @@ Objects have access to their type at runtime. There is an
 ``of`` operator that can be used to check the object's type:
 
 .. code-block:: nimrod
-
   type
     TPerson = object of TObject
       name*: string  # the * means that `name` is accessible from other modules
@@ -68,6 +66,8 @@ Objects have access to their type at runtime. There is an
     student: TStudent
     person: TPerson
   assert(student of TStudent) # is true
+  # object construction:
+  student = TStudent(name: "Anton", age: 5, id: 2)
 
 Object fields that should be visible from outside the defining module have to
 be marked by ``*``. In contrast to tuples, different object types are
@@ -161,12 +161,7 @@ An example:
       of nkIf:
         condition, thenPart, elsePart: PNode
 
-  var
-    n: PNode
-  new(n)  # creates a new node
-  n.kind = nkFloat
-  n.floatVal = 0.0 # valid, because ``n.kind==nkFloat``
-
+  var n = PNode(kind: nkFloat, floatVal: 1.0)
   # the following statement raises an `EInvalidField` exception, because
   # n.kind's value does not fit:
   n.strVal = ""
@@ -288,30 +283,22 @@ Procedures always use static dispatch. For dynamic dispatch replace the
 
 .. code-block:: nimrod
   type
-    TExpr = object of TObject ## abstract base class for an expression
-    TLiteral = object of TExpr
+    PExpr = ref object of TObject ## abstract base class for an expression
+    PLiteral = ref object of PExpr
       x: int
-    TPlusExpr = object of TExpr
-      a, b: ref TExpr
-      
-  method eval(e: ref TExpr): int =
+    PPlusExpr = ref object of PExpr
+      a, b: PExpr
+
+  # watch out: 'eval' relies on dynamic binding
+  method eval(e: PExpr): int =
     # override this base method
     quit "to override!"
   
-  method eval(e: ref TLiteral): int = return e.x
-
-  method eval(e: ref TPlusExpr): int =
-    # watch out: relies on dynamic binding
-    return eval(e.a) + eval(e.b)
+  method eval(e: PLiteral): int = e.x
+  method eval(e: PPlusExpr): int = eval(e.a) + eval(e.b)
   
-  proc newLit(x: int): ref TLiteral =
-    new(result)
-    result.x = x
-    
-  proc newPlus(a, b: ref TExpr): ref TPlusExpr =
-    new(result)
-    result.a = a
-    result.b = b
+  proc newLit(x: int): PLiteral = PLiteral(x: x)
+  proc newPlus(a, b: PExpr): PPlusExpr = PPlusExpr(a: a, b: b)
   
   echo eval(newPlus(newPlus(newLit(1), newLit(2)), newLit(4)))