Re: Restricting input depending on output

   X-PH: V4.4@mr3
   From: Saied Tazari <Saied.Tazari@zgdv.de>
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   Cc: www-ws@w3.org
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   > Why not introduce a
   > "select" step that picks one from a list?  Then you could have a sequence
   > 
   >     GetPostitCompositionPrerequisites
   >       
   >       >out>  availableLocationList_Out
   >             =availableLocationList_In
   >              >in>
   > 
   >                PickOne
   > 
   >                  >out>  selectedLocationList_Out
   >                        =selectedLocationList_In
   > 
   >                           >=> 
   > 
   >                               StickPostit
   > 
   > You would need two 'sameValues' declarations to make this work.
   > 
   >                                              -- Drew McDermott

   Two problems:

   . That is shifting the problem from
	 (availableLocationList_Out --here--> selectedLocationList_In)
      to
	 (availableLocationList_In --here--> selectedLocationList_Out)
      despite making the sequence longer.

The same solution works in both places.

   . The natural meaning of PickOne says that only one location is
      selected but our requirement is that the value to be provided
      for selectedLocationList_In must be a **subset** of the value
      provided for availableLocationList_Out in the preceeding step.

Sorry, I missed that.  Since my hypothetical PickOne step is, indeed,
hypothetical, just rename it "PickSome" and the problem is solved.

                                             -- Drew McDermott