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From: shiva@well.sf.ca.us (Kenneth Porter)
Newsgroups: comp.lang.postscript
Subject: Re: transfer function (was Re: Help!)
Summary: settransfer not commutative
Message-ID: <20947@well.sf.ca.us>
Date: 4 Oct 90 18:37:16 GMT
References: <JWZ.90Sep13112918@kolyma.lucid.com> <20829@well.sf.ca.us> <JWZ.90Sep28201446@kolyma.lucid.com>
Lines: 26



Actually, I think you want to put the old transfer function at
the *end* of the new transfer procedure to get the right
effect, since there's no guarantee that the two procedures are
commutative:
 
/newstuff { .... } def
% remember to disable packing so put can write into executable array
false setpacking        % real code should save current packing state
{ newstuff 0 exec } dup 1 currenttransfer put settransfer
 
The resulting transfer proc is
 
{ newstuff <oldtransfer> exec }
 
Is currenttransfer a variable or an operator?  If an operator, then the
following doesn't work:
 
{ currenttransfer } bind
 
If it's a variable, then you can just do this:
 
{ //currenttransfer exec }
 
Ken (shiva@well.sf.ca.us)