Parlando con Andrea Zaccagnini a proposito di REXX,
 Phil Crown scrisse:

 PC> I am just learning REXX, but you should probably be using == not =?

 PC> /**/

 PC> a   = 1
 PC> aa  = 2
 PC> b   = 3
 PC> bb  = 3

 PC> if((a == aa) | (b == bb)) then
 PC> do
 PC> if(a == aa) then
 PC> say "a="a" aa="aa
 PC> if(b == bb) then
 PC> say "b =" b "bb ="bb
 PC> end

Awful: I just tested this code, and works fine! Where have you read about
the need for the == operator? 

 PC> Now, to add to the confusion, this line works,

 PC> say "b =" b "bb ="bb

 PC> but this one does not?

 PC> say "b ="b"bb ="bb

 PC> arghh! :-)

That's funny, really. As far as I know 

say "b =" b "bb ="bb

must return:

b =(value of b)bb =(value of bb)

The other token,

say "b ="b"bb ="bb

should give exactly the same output, because:

start quoting SAA Procedure Language REXX Reference, by W.D.Ashely:
___________________________________________________________________
   o Concatenation 

     ||             concatenate (with no blank in between) 
     (juxtaposition)concatenate (with no blank in between) 
     (blanks)       concatenate with just one blank between 

                    Examples: 

                    myvar1 = "the"
                    myvar2 = " time"
                    say "Now"     "is
"myvar||myvar2" for all good men ..."
                             ÀÄÂÄÙ    À´    ÃÙ     À´
                                      ³           ÀÄÄÄ¿
                            (blanks)   ³   (||)         
                                                     (juxtaposition)
                                 (juxtaposition)
                    
                    displays: 

                    "Now is the time for all good men ..."
 ___________________________________________________________________
stop quoting

But that's the surprising result of some variations on this theme:

say "b =" b "bb ="bb
b = B bb =BB
  ................................................ REXXTRY.CMD on OS/2
say "b ="b"bb ="bb
  Oooops ! ... try again.     Invalid hexadecimal or binary string
  rc = 15 ........................................ REXXTRY.CMD on OS/2
say "b ="||b||"bb ="||bb
b =Bbb =BB
  ................................................ REXXTRY.CMD on OS/2
say "b ="b"bb ="||bb
  Oooops ! ... try again.     Invalid hexadecimal or binary string
  rc = 15 ........................................ REXXTRY.CMD on OS/2
say "b ="b||"bb ="bb
  Oooops ! ... try again.     Invalid hexadecimal or binary string
  rc = 15 ........................................ REXXTRY.CMD on OS/2
say "b ="||b||"bb ="bb
b =Bbb =BB
  ................................................ REXXTRY.CMD on OS/2
say "b ="||b"bb ="bb
b =Bbb =BB
  ................................................ REXXTRY.CMD on OS/2


say "b ="||b"bb ="bb
         ^^
This is, out of every doubt, the critical concatenation. It seems that
an implicit concatenation in this position causes a wrong interpretation
of the token by REXX. And I've never heard or read about it before...
It seems a bug...

Bye,
Andrea Zaccagnini
... "And I Thyresias I have presuffered all" (Eliot)
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