Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ncar!asuvax!cs.utexas.edu!uunet!willett!ForthNet
From: ForthNet@willett.UUCP (ForthNet articles from GEnie)
Newsgroups: comp.lang.forth
Subject: ANS TC Magnet for Interpreter
Message-ID: <270.UUL1.3#5129@willett.UUCP>
Date: 16 Jan 90 00:56:41 GMT
Organization: Latest Link in ForthNet Chain (Pittsburgh, PA)
Lines: 46

Category 10,  Topic 24
Message 7         Sun Jan 14, 1990
F.SERGEANT [Frank]           at 22:44 CST
 
  re: temporary base changes

  I loved Wil Baden's words on the order of $XX and $XXXX for forcing the base
for that one number to hex.  His trick relied on setting WIDTH to 3 and 5
respectively for their definitions.  That way, $12 $FF $7E etc would all match
to $XX and $1234 $FFEE etc would match to $XXXX.  I think this can be done in
any Forth that has WIDTH, and without changing NUMBER or anything in the
kernel.

  Pygmy does not have WIDTH.  It saves the full name (up to 31 characters) and
does not need to do set any other bits in the header. (This may save some
time.  It certainly makes browsing the dictionary with DUMP and DU more
pleasant as the names are easily readable.)  In version 1.2 of Pygmy I changed
NUMBER to recognize the prefix $ as indicating HEX for that one number (and
the prefix ' for indicating an ascii character.  LOAD in all versions of Pygmy
restores the base to decimal before returning, so you always know what base
the screen starts off in.

  So often I want just one number to be in hex, usually to set or test a bit
pattern, and would prefer the rest of the numbers in decimal. So, yes, I am
using this and I like it.  I hate the clutter of saying something like  
DECIMAL .......  HEX FC DECIMAL ........ and can now say just  ........  $FC
.............

  I am enjoying this new convenience in new code that I write.  Gee, saying
something like  H#1234 sure is ugly!  I'm used to the dollar sign from many
years of Motorola processor exposure, and also to an X from IBM 360/370
assembler work (eg X'1234').  Of the two I think the dollar sign is at least
as pretty, and since it is simpler, it wins.

  For my double numbers I use   D' 1234   as I haven't built any other
mechanism into the kernel.  This has been satisfactory so far. Sometimes I
might want to express a bit pattern in binary.  I don't, however.  I just use
hex.  I think I wouldn't bother changing NUMBER to recognize either a forced
octal or binary.  If I had to use octal or binary and 2 BASE !  or  8 BASE ! 
wouldn't do, I suppose I would define something like B' or O'  ( eg   B'
01100011   or  O' 137 ).

  -- Frank
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