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From: John Deubert <john@acumentraining.com>
Organization: Acumen Training
Newsgroups: comp.lang.postscript
Date: Mon, 7 Jan 2013 06:38:16 -0800
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Subject: Re: save restore problem - is it possible to use it in this way?
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On 2013-01-04 18:10:00 +0000, luser- -droog said:

> On Friday, January 4, 2013 10:39:09 AM UTC-6, wojt...@gmail.com wrote:
> 
>> Should it be ok too?
>> 
>> If yes then probably there is something wrong with the stack between 
>> save and restore and restore have wrong data on the stack? How to check 
>> it? PS file has more than 1k lines :/
> 
> If you can't trust the stack, trust the dictionary.
> 
> /saveobjectA save def
> 
> /saveobjectB save def
> 
> saveobjectB restore
> 
> saveobjectA restore

I'd go a step further and say you should absolutely not use the operand 
stack to store the save objects created by save and used by restore; 
too much opportunity for things to go wrong. It is much better to put 
the objects into a key-value pair, as droog says above.

If you absolutely must leave the saveobject on the stack (perhaps 
because you're working with existing code written by someone else), 
then you can test the top of the stack before executing restore:

dup type /savetype
{ restore }{ ... handle or head off typecheck error here ... } ifelse

- John

-- 
========
John Deubert
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