🚀 go-pugleaf

In article <1909@chinacat.Unicom.COM> woody@chinacat.Unicom.COM (Woody Baker @ Eagle Signal) writes:
>In article <38972@netnews.upenn.edu>, jeffe@eniac.seas.upenn.edu (George Jefferson ) writes:
>> Is there a way to store a value at some low level which is not
>> destroyed by restore?
>I seem to remember that on at least on older version of PS, there was a bug
>that allowed you to do this.  I think it was something like if you created
>a string, then put a character into it with put, it would survive a
>save/restore pair.  I know that Don Lancaster published some thing about it,
>and even wrote code to use it, but IT IS A BUG AND IS NOT REPEATABLE
>unless you have the buggy interpreter.
>
>i.e.  Not wise to write code for others use that depends on it.

Yeah, this is referred to in a footnote on p.43 in Section 3.7, "VIRTUAL
MEMORY," of the Red Book (1st ed):

	In the current PostScript design, restore actually
	does not undo changes made to the elements of strings.
	We consider this behavior to be a defect, and we do
	not recommend that PostScript programs take advantage
	of it.

Leland Woodbury
-- 
INTERNET: leland@cs.columbia.edu
  USENET: ...!columbia!cs.columbia.edu!leland
  BITNET: leland%cs.columbia.edu@cuvmb
  USMAIL: Columbia Univ., 457 CS, 500 W. 120 St., NYC 10027-6699