RE: RPG read loops

[Alan Campin <Alan.Campin@xxxxxxx>]

Double the code and double the complexity. A simple 

Setll
DoU 1 = 0
        Read
        If Eof or Key Change
                Leave
        EndIf
        .....
EndDo

Why put the logic in two places? My opinion only. 

-----Original Message-----
From: Paul Morgan [mailto:pmorgan@xxxxxxxxxxxxxx]
Sent: Tuesday, February 01, 2005 1:27 PM
To: rpg400-l@xxxxxxxxxxxx
Subject: RPG read loops


Almost all of the code in the current Leave / Iter thread showed a loop
like:

DoU F3 or F12
   exfmt
   If Not (F3 or F12)
      //  do something
   EndIf
EndDo

This only has one exfmt statement inside a DoU loop.  A similar file read
loop would be:

DoU %EoF
   Read
   If Not %Eof
      // do something
   EndIf
EndDo

which has one read statement inside of a DoU loop.  Isn't there a better way
of coding loops with more than one read/exfmt like:

exfmt
DoW Not (F3 or F12)
   //  do something
   exfmt
EndDo

or

Read
DoW Not %Eof
   // do something
   Read
EndDo

or

SetLL
ReadE
DoW Not %Eof
   // do something
   ReadE
EndDo

Most programmers seem to code with the single read/exfmt style which IMHO
complicates the code.  In a DoU/Read loop the body of the loop is nested two
deep inside the DoU and an If statement.  In a Read/DoW/Read loop the body
of the loop is nested one deep inside a DoW.  Doesn't this reduction in the
nesting of the body of the loop improve the program?  Readability is
improved.  Performance is also improved (although minor) with the removal of
one test against the end of loop.

Other programmers I work with are adamant about not coding more than one
read statement.  Why is coding more than one read statement such a problem?

Paul

--
Paul Morgan
Senior Programmer Analyst - Retail
J. Jill Group
100 Birch Pond Drive, PO Box 2009
Tilton, NH 03276-2009
Phone: (603) 266-2117
Fax:   (603) 266-2333