GETPREVALIDATE()
 Prevalidate a Get object
------------------------------------------------------------------------------
 Syntax

     GETPREVALIDATE(<oGet>) --> lSuccess

 Arguments

     <oGet> is a reference the current Get object.

 Returns

     GETPREVALIDATE() returns a logical value indicating whether the Get
     object has been prevalidated successfully.

 Description

     GETPREVALIDATE() is a Get system function that validates the Get object
     for editing, including evaluating Get:preBlock (the WHEN clause) if it
     is present.  The logical return value indicates whether the Get has been
     prevalidated successfully.

     Get:exitState is also set to reflect the outcome of the prevalidation:

     Get:exitState Values
     ------------------------------------------------------------------------
     Getexit.ch   Meaning
     ------------------------------------------------------------------------
     GE_NOEXIT    Indicates prevalidation success, okay to edit
     GE_WHEN      Indicates prevalidation failure
     GE_ESCAPE    Indicates that a CLEAR GETS was issued
     ------------------------------------------------------------------------

     Note that in the default system, a Get:exitState of GE_ESCAPE cancels
     the current Get and terminates READMODAL().

 Files:  Library is CLIPPER.LIB, source file is Getsys.prg.