Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!cs.utexas.edu!rutgers!gatech!hubcap!grimlok
From: grimlok@hubcap.clemson.edu (grimlok)
Newsgroups: comp.lang.rexx
Subject: MVS REXX, Rexx in general - efficiency questions
Message-ID: <5805@hubcap.clemson.edu>
Date: 20 Jun 89 14:53:40 GMT
Organization: Clemson University, Clemson, SC
Lines: 37

In an effort to learn Rexx and start a conversion of some very UGLY
Clists, I have been writing some of the less ugly smaller clists in
Rexx.                                    

Knowing that Rexx is interpreted, and knowing that our Reference manual
is backordered, I encountered a few questions of efficiency which I am
unable to answer.

Here are a few:
 
 1) Is copies(" ",80) any worse or better than copies("  ",40) or for
    that matter copies("    ",20)? The first is obvious that I want an
    80 character string consising of blanks, it gets less obvious as we
    go down. Probably the best thing is to set a variable to a constant
    like spaces = "    ...80 spaces..." but you have to split it up and
    it becomes unreadable and the chances of mis-counting are great.
    In short, how does copies() really work?
 
 2) Given that the comparision x = y will give me the same results
    as x == y for the possible values of x and y in my program, is one
    "better" than the other?
 
 3) Are logical operators short circuiting? That is, if I say:
    if x | y | z then ... and x is true, are y and z evaluated and or'd?
    If z is true 90% of the time and x and y only 20%, should I put
    if z | x | y then ... to save time, even though it is slightly less
    intuitive? I know from seeing select traced that when a when
    expression is true the other cases are bypassed. 

Thanks in advance.


-- 

'I just couldn't convince the voters that Dukakis was Greek for
"Bubba".' -- Lloyd Benson explaining why the Democrats didn't carry
Texas