Parameter Checking
------------------

Author: Gabrielle Allen
Date: February 2001

Why
---

Need to firm up and document the parameter checking from parameter
files, and for steerable parameters, and recovery from parameter 
files


Definitions
-----------

Parameter syntax:

   parameter (global parameters)
   label::parameter

Where label indicates a implementation or thorn.
 
Parameter checking levels set by command line

  -parameter-level=<level>

where level is

  relaxed: only error for out of range
  normal: error for parameters from an active thorn which are not found
  strict: error for anything wrong


Specification
-------------

Steered parameters:

  steered parameters should never cause errors

From a parameter file:


if (label is active implementation and/or thorn)

   if (active implementation with different name to implementing thorn)

	set parameter
	
   end if

   if (active thorn)

	set parameter

   end if

   if (succeeding in setting for BOTH active thorn and active implementation)

      if (parameter check == strict or normal)
	 ERROR
      else if (parameter check == relaxed)
         WARN
      end if
   
   else if (couldn't set for EITHER active thorn or active implementation)
 
      /* If both active which one do I report about here? */

      if (parameter name valid)	

	 if (changing value of a non steerable parameter at recovery)
	    if (parameter check == strict or normal)
	       ERROR 
            else if (parameter check == relaxed)
	       WARN
            end if
	 else
            if (out or range) ERROR
	 endif

      else /* parameter name not valid */

         if (parameter check == strict or normal)
            ERROR
         else if (parameter check == relaxed)
           WARN
         end if

      end if
   end if

else if (label exists but not active)

   if (parameter check == strict)
      ERROR
   else if (parameter check == normal)
      WARN
   else if (parameter check == relaxed)
      NOTHING
   end if

else

   set global parameter

   if (parameter name valid)	

      if (changing value of a non steerable parameter at recovery)
         if (parameter check == strict or normal)
            ERROR 
         else if (parameter check == relaxed)
	    WARN
         end if
      else
         if (out or range) ERROR
      endif

   else /* parameter name not valid */

      if (parameter check == strict or normal)
         ERROR
      else if (parameter check == relaxed)
         WARN
      end if

   endif

end if



Notes
-----

The correct syntax is to specify a parameter using its implementation
if it is public or protected, and its thorn name if it is private.

However, we allow parameters to be specified wrongly using either
an implementation or thorn name, but strongly recommend people to use
the correct syntax, especially is they are working with multiple 
thorns for a single implementation.


Questions:
---------

1) implementations/thorns with the same name as described above

2) is there any way to set the parameter checking level apart from 
   at the command line?