vbtkit/src/lego/SwitchVBT.i3

 Copyright (C) 1992, Digital Equipment Corporation                         
 All rights reserved.                                                      
 See the file COPYRIGHT for a full description.                            
                                                                           
 Last modified on Tue Jun 15 15:51:00 PDT 1993 by meehan                   
      modified on Fri Jan 29 23:05:20 PST 1993 by mhb                      
      modified on Tue Jun 16 13:08:12 PDT 1992 by muller                   

<* PRAGMA LL *>
<* PRAGMA SUBTYPE *>

 A SwitchVBT is a switch version of Trestle's ButtonVBT. 


INTERFACE SwitchVBT;

IMPORT ButtonVBT, FeedbackVBT, MultiClass, VBT;

TYPE
  <* SUBTYPE T <: MultiFilter.T *>
  T <: Public;
  Public = ButtonVBT.T OBJECT
           METHODS
             <* LL.sup <= VBT.mu *>
             init (f: FeedbackVBT.T): T;
             <* LL.sup = VBT.mu *>
             callback (READONLY cd: VBT.MouseRec);
           END;

 The call v.init(f) initializes v as a SwitchVBT with child
   f. The multi-child of f is marked as v's multi-child too.


   The default callback method is a no-op. 


 The following type is useful for creating switches that have the
   same internal structure as a SwitchVBT.T; namely, a Filter.T
   whose child is a FeedbackVBT.T. 


TYPE
  MC <: MultiClass.Filter;

 The following procedures are useful for some VBTkit switches
    to use as their default ButtonVBT methods: 


PROCEDURE Pre (v: ButtonVBT.T);
<* LL.sup = VBT.mu *>

 Equivalent to: Feedback.Excited (Filter.Child(v)) 

PROCEDURE Post (v: ButtonVBT.T);
<* LL.sup = VBT.mu *>

 Equivalent to: Feedback.Normal (Filter.Child(v)) 

PROCEDURE Cancel (v: ButtonVBT.T);
<* LL.sup = VBT.mu *>

 Equivalent to: Feedback.Normal (Filter.Child(v)) 

END SwitchVBT.