ComponentView(3U)					    InterViews Reference Manual 					 ComponentView(3U)

NAME

       ComponentView - base class for views of objects that model domain-specific elements

SYNOPSIS

       #include <Unidraw/Components/compview.h>

DESCRIPTION

       ComponentView  is an abstract base class for views of component subjects.  Component views provide a specialized presentation of the infor-
       mation in the component subject to which they are attached.  Usually there is at least one view subclass defined for each subclass of  com-
       ponent subject.

PUBLIC OPERATIONS

       virtual void Interpret(Command*)
       virtual void Uninterpret(Command*)
	      These  operations call the corresponding subject operations by default.  They are included in the component view protocol for conve-
	      nience, since other objects often deal with component views rather than their subjects.

       virtual void Update()
	      Notify the view of a change in some state that it depends on, normally state  in	the  subject.	This  operation  does  nothing	by
	      default.

       virtual Component* GetParent()
	      Return  the  view's  parent, if any.  Like component subjects, component views may be structured hierarchically, and their structure
	      may or may not reflect that of their subject.

       Component* GetSubject()
	      Return the component view's subject.

       virtual void First(Iterator&)
       virtual void Last(Iterator&)
       virtual void Next(Iterator&)
       virtual void Prev(Iterator&)
       virtual boolean Done(Iterator)
	      Operations for iterating over the component view's children, if any.  First and Last initialize an iterator to point to  the  begin-
	      ning and end of the list of children, respectively.  Next increments the iterator to point to the following child, while Prev decre-
	      ments the iterator to point to the preceding child.  Done returns whether or not the iterator points beyond the first or last  child
	      in the list.

       virtual ClassId GetClassId()
       virtual boolean IsA(ClassId)
	      GetClassId  returns the unique class identifier for the ComponentView subclass, while IsA returns whether the instance is of a class
	      or subclass corresponding to the given identifier.  IsA typically checks the given identifier against the instance's own (as defined
	      by  its  GetClassId  operation) and, failing that, calls its parent classes' IsA operation.  All subclasses must redefine GetClassId
	      and IsA to ensure that their identifiers are unique and that view category information is defined  properly.   See  classes(3U)  for
	      more information on class identifiers and view categories.

PROTECTED OPERATIONS

       ComponentView(Component* subject = nil)
	      The  constructor	initializes the component view's subject pointer to the given value.  The view will also attach itself to the sub-
	      ject if the argument is non-nil.

       virtual void SetSubject(Component*)
	      Set the component's subject pointer to the given value.  By default, this operation does not call  Attach  or  Detach  on  the  sub-
	      ject(s).

       virtual void SetParent(Component* child, Component* parent)
	      Notify  a  child	component  that  it  has a new or different parent.  This operation does nothing by default.  Composite components
	      should call this function in their structure-modifying operations, and components that keep information about their  parents  should
	      redefine it to update this information.

SEE ALSO

       Command(3U), Component(3U), Iterator(3U), classes(3U)

Unidraw 							  20 August 1990						 ComponentView(3U)