Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!rutgers!njin!princeton!phoenix!pucc.Princeton.EDU!wagner
From: wagner@pucc.Princeton.EDU (John Wagner)
Newsgroups: comp.lang.rexx
Subject: Re: A Suggestion For Adding Function Pointers To REXX
Message-ID: <13623@phoenix.Princeton.EDU>
Date: 6 Feb 90 14:53:06 GMT
References: <26534@cup.portal.com> <25545@cup.portal.com> <5344.25b20330@elroy.uh.edu>
Sender: news@phoenix.Princeton.EDU
Lines: 76

In article <26534@cup.portal.com>, Will@cup.portal.com (Will E Estes) writes:

> (1) I dare anyone to write in REXX a general purpose binary sort
> routine that acts on *any* REXX array and uses the PROCEDURE
> keyword on the subroutine.
> 
> (2) I dare anyone to write in REXX a general purpose binary sort
> routine that acts on *any* REXX array without the PROCEDURE
> keyword on the subroutine that doesn't look uglier than Bill the
> Cat when he wakes up in the morning.
> 
> The routine for (1) can't be written.  And of course using the
> PROCEDURE keyword is a must for anyone who wants to write
> structured code.

Will, This is simply not true.  You may not like how the code looks, but
that is different than saying it cannot be done.  Remember that the
SAA restriction on using "INTERPRET 'name: procedure expose' var"
is an IBM restriction that is not part of the language.  Don't use
the IBM manuals for REXX when you are trying to understand what
the language is supposed to be.  The only source for that information
is Colishaw's book "The REXX Language, A Practical Approach to 
Programming". 

> If you don't use the PROCEDURE keyword at all, then you can use
> INTERPRET liberally throughout the subroutine to do just about
> anything.  But this is a totally unacceptable solution for any
> number of reasons: 1) the code looks like hell; 2) it is not
> efficient; 3) it is not supported in the compiler; 4) it requires
> you to not use the PROCEDURE keyword which exposes all of the
> caller's environment, and this is hack programming at its worst.

I don't know what environment you are using REXX in, but I
would guess that it is not VM/CMS since you seem to be missing the
"feel" of it.  This comes through in the way you state your dare.
You have assumed that the correct answer is the ability to write
all code in REXX.  Colishaw never meant for that to be the case.
REXX is a blend of high level code with system dependent function
packages.  You cannot separate the two.

The appropriate response to your dare is that two forms come to mind.
The first is:

    call sort 'Stem_to_sort.' , 'Stem.' < , 'Ascending' >
                                        < , 'Descending' > 

This places the sorted values found in 'Stem_to_sort.' into the stem
'Stem.' with 'Stem.0' containing the number of values.  The third 
parameter just specifies the sort order.  It uses the standard REXX
technique of only making the first character significant so you could
code 'DownDamnIt' it you wanted.  The default would be ascending.

This procedure would sort any value starting with 'Stem_to_sort.' so
you might want to add another parameter to specify valid tail types
(Any, Numeric, Character, etc.).  It could also be used to sort some
portion of a stem's values by specifying a partial tail, as in

     call sort 'Unsorted.Array.' , 'Sorted.array.' , 'D'

If what you want to do is sort words in a string you use

     SortedString = sortwords(string <, 'Ascending' >  )
                                     <, 'Descending' > )

This one can be done using a REXX procedure, but is quicker in machine
code.
    
Function packages are meant to do exactly what their name implies, provide
function not found in the base REXX language.  They are meant as the way
to make REXX extensible.

You might want to take a look at a REXX function package available from
Berthold Pasch (BITNET:  PASCH@DHDIBM1  VNET: PASCH at GYSVMHD1).  The
package is known as XVAR (eXtended VARiable support) and is for REXX
programs in CMS.  It allows you to access copies of the variables in a
callers routine (both R/O and R/W).  Using this package it is possible