Re: %TLOOKUP

["mlazarus@xxxxxxxx" <mlazarus@xxxxxxxx>]

Hans,

> I understand what you're saying. It's just that we suspect that 
tables are relics of an older era, and that there's not much need to 
do much with them. Functionally, there's nothing that you can do 
with tables that you can't also do with arrays. And since arrays are 
so much more powerful anyways, why bother limiting yourself by using 
a table?

> On the other hand, if there really is some overwhelmingly compelling 
reason that tables should be enhanced, I'm all ears!

 One word: "simplicity".

 I'll say at the outset that if I were designing the language from the
ground up, there would be no diference between a table and an array.  But
since there is this concept built into the language, I may as well use it. 

 I recently had occasion to use it, so it's fresh in my mind.  I have a
simple compile time table with static data that contains the "columns":
Source type, Type code and Description.  Source type is unique.  Type code
can repeat and Description will be ignored by the program (it's only for
the programmer's edification.)

 The requirements are simple:  If it's found in the table, use the
alternating table's value.  So the code looks like this:
IF   %TLookup( SrcAttribute: TabSrcTypes: TabTypeChars ) = *Off  ;
  RETURN  '-'                                                    ;     
ELSE                                                             ;     
  RETURN  TabTypeChars                                           ;     
ENDIF                                                            ;     

 With arrays this would require a separate lookup, an additional variable
(the index), code to reset the index.  It's not a large amount of code
difference, but it is slightly more complex.

 Can the ALT keyword be used w/ compile time arrays?  (I still want to keep
the values side-by-side on the bottom.)  If not, then I would have to
define it as an OVERLAYed DS, but it would still require using an index
variable; not as elegant.

 -mark
                                                                  


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