KnowledgeBase 00048: User Written Conversion Codes

This article was originally published as a Tip of the Week.

QM provides the ability for developers to add new conversion codes that can then be used in all situations where the standard built-in codes can be used.

The Conversion Subroutine

A user written conversion code is a subroutine declared as

   SUBROUTINE NAME(RESULT, SRC, STATE, IS.OCONV) 

The subroutine must be catalogued in a mode that makes it available to all accounts in which it is to be used.

Example

The example below is a base 36 encoding where a non-negative numeric value is encoded to a series of alphanumeric characters in the minimum possible space.

subroutine b36(result, (src), state, is.oconv) 
$catalogue b36 global 
   if is.oconv then 
      result = '' 
      if src matches '1N0N' then 
         loop 
            result = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ'[rem(src, 36)+1, 1] : result 
            src = idiv(src, 36) 
         while src 
         repeat 
         state = 0 
      end else 
         state = 1 
      end 
   end else 
      result = 0 
      for i = 1 to len(src) 
         j = index('0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ', upcase(src[i,1]), 1) - 1 
         if j < 0 then 
            state = 1 
            result = '' 
            return 
         end 
         result = result * 36 + j 
      next i 
      state = 0 
   end 
   return 
end 

Using the New Code

The user written conversion code can be used in all places where a built-in code can be used. The conversion name is the same as the catalogue name of the conversion subroutine with a U prefix added. For example, the base 36 encoding shown above could be used as

   ENCODED.CLIENT.NO = OCONV(CLIENT.NO, "UB36") 

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