Path: utzoo!attcan!uunet!shakti!shri
From: shri@ncst.ernet.in (H.Shrikumar)
Newsgroups: comp.lang.forth
Subject: Re: Data Structures
Summary: Pointer In Pointer Out ...
Message-ID: <978@shakti.ncst.ernet.in>
Date: 2 Oct 90 11:31:53 GMT
References: <9009220053.AA13718@ucbvax.Berkeley.EDU>
Reply-To: shri@ncst.in (H.Shrikumar )
Organization: National Centre for Software Technology, Bombay, INDIA
Lines: 36

In article <9009220053.AA13718@ucbvax.Berkeley.EDU>
 wmb%MITCH.ENG.SUN.COM@SCFVM.GSFC.NASA.GOV replies to ...

>> How do I get "adr len" on the stack?  The operation is defined for strings
>> defined with " , but what about strings in memory?  I can only get the
>
>The operators for manipulating strings should be as general as possible,
>and independent of how those strings happen to be encoded when stored
>in memory.  

   Yup. Also could overload the same ideogram for same action on
strings of differnt types, the correct word being selected by the 
value of a variable called TYPE, (much as numbers are interpretted
according to current value of BASE). (* I saw a feature with similar
intensions first in Mikael Patels xforth.)

   Also, another thing I am trying out in myForth is that all operators
which take a pointer, should return a pointer.

   The idea is  ... say a word that takes a string and replaces "$1" by
"gus" ("fun$1prat" becomes "fungusprat") would take a pointer to the
string, do its job and return a pointer to the new string.

   The retuned pointer may or may not be the same, the program must not
make assumptions about it (sorry hackers :-).

   This is not too difficult to implement, only a little inefficient,
and gives a clean semantics. (IMHO, worth it.)

   For eg. the string could be in ROM, and when somebody tried to
modify it, the word could (if so designed) copy it into RAM
"transparently", change it and return a new pointer. This could also
become the basis for several other features (memory de-fragmentation
etc.)

-- shrikumar ( shri@ncst.in )