Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!decwrl!alien.dec.com!postpischil
From: postpischil@alien.dec.com (Always mount a scratch monkey.)
Newsgroups: comp.sys.hp
Subject: HP-28S program to manipulate programs
Message-ID: <8902131556.AA26837@decwrl.dec.com>
Date: 13 Feb 89 18:56:00 GMT
Organization: Digital Equipment Corporation
Lines: 31

Benoit Menendez asks for a way to create a program object which depends
partially on an argument. 

In the code:

<< -> i
    <<
	<< -> x << x i + >> >>
    >>
>>

realize that << -> x << x i + >> >> is an object, and all that happens
to this object when the program is evaluated is that it is placed on the
stack.

Since we want to create a program object not known at the time of writing, we
cannot simply place a copy of an object on the stack.  We therefore need
a built-in function which returns a program object.  I think the only suitable
function is STR->, which takes a string and can return any object(s).

So one possibility is:

<< "<< -> x << x " SWAP ->STR + " +" + STR-> >>

This will perform the requested function, although it is not necessarily
a good way to solve a problem.  (Actually, there are some objects for which
->STR STR-> will not return the original object, such as strings with embedded
quotes, and the above program will not work with such objects.)


				-- edp