Bug in operator restore in Apple LW?

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#1178

From: Johan Ihren
Date: Wed, 11 Oct 1989 23:53

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In the PostScript Reference Manual, the cause of the error invalidrestore
is said to be that the operand-, dict- or execstack contains composite
objects whose value were created later than the saveobject that is being
restored. Take a look at this example:

%!
10 dict begin
  /saveob save def
  userdict /keepdict currentdict put
end keepdict begin
  saveob restore
  (ok.\n) print

This program produces an invalidrestore, atleast on the LW+ I used.
If the line starting with end is removed, it works.
But that line only pops the dict off the dictstack and pushes it back again!
Is this a bug or am I thinking wrong?
Thankful for any explanations, either here or to me or to
f86.fredric-ihren@vera.nada.kth.se

Johan Ihren
Royal Institute of Technology, Stockholm, Sweden.

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Path: arc1-ca.pugleaf.net!utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!wuarchive!wugate!uunet!bloom-beacon!eru!luth!sunic!draken!johani
From: johani@nada.kth.se (Johan Ihren)
Newsgroups: comp.lang.postscript
Subject: Bug in operator restore in Apple LW?
Keywords: restore
Message-ID: <2053@draken.nada.kth.se>
Date: 11 Oct 89 23:53:08 GMT
Organization: Royal Institute Of Technology, Stockholm, Sweden
Lines: 22