APP008.TXT  TestPoint Application Note


APP008A.TST  Associated Source File  example 1


APP008B.TST  Associated Source File  example 2


(c) Capital Equipment Corporation 1995





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Putting the User in Control. 





Mapping Strings to Numbers and Numbers to Strings.


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TestPoint creates event driven applications and the obvious 


difference between running a DOS program and an event driven program 


is that the end user is in control.  A DOS program prompts for data 


entry and controls every interaction.  An event driven program 


patiently waits for the user to enter a value or make a choice from a 


range of choices provided on the screen.  This is one of  the 


fundamental ideas behind the use of an Action List in TestPoint.  


When the user makes a selection it creates an event which puts the 


Action list into action. 





Event driven applications commonly have to deal with a wide range of 


user choices, options and entries.  This could lead to a long series 


of If/Then or If/Then/Else statements.  The conditional statements 


appear to be necessary  to determine what action to take based on the 


user input.  However, using TestPoint's selector is a simple way to 


eliminate many If/Then and If/Then/Else statements.   This technique 


allows you to condense many conditionals into a single action line. 





This is the way it works.  Whenever you need to map a set of strings 


to a set of numbers or assign a list of commands to a set of menu 


items, choose the selector object then enter the settings such that - 





        labels =strings or menu items available to the user


        values = numbers or commands you need





You can now use the selector as a parameter in an action line.  If  


the action list is the action list for the selector object, only one 


line is required to map the command and execute the action.  This is 


a particularly good method for creating a set of commands for an 


instrument library. 





The TestPoint associated source files provide two practical examples.  


The first example maps a set of menu commands to alpha numeric 


instrument commands and sends the selected command to the instrument.  


The second example converts entered values to engineering units.