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Re: What is the best way to work with a dictionary

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Op zaterdag 13 jul 2013 22:32 CEST schreef Helge Blischke:

> Cecil Westerhof wrote:
>
>> Until now I wrote functions like:
>> /ellipse { % x y unitX unitY colour
>> 5 dict begin
>> /colour  exch def
>> /unitY   exch def
>> /unitX   exch def
>> /y       exch def
>> /x       exch def
>>
>> gsave
>> newpath
>> colour  setrgbcolor
>> x  y  translate
>> unitX  unitY  scale
>> 1  1  1  0  360  arc closepath fill
>> stroke
>> grestore
>> end
>> } def
>>
>> I just saw in ‘PostScript Drawing: An Economist's Guide’ that it
>> also should be possible to do it in the following way: /ellipse { %
>> x y unitX unitY colour << /colour exch
> % operand stack at this point:
> % x y unitX unitY color /color mark
>> 		             def
>> /unitY   exch def
>> /unitX   exch def
>> /y       exch def
>> /x       exch def
>>>> begin
>> gsave
>> newpath
>> colour  setrgbcolor
>> x  y  translate
>> unitX  unitY  scale
>> 1  1  1  0  360  arc closepath fill
>> stroke
>> grestore
>> end
>> } def
>>
>> Which of the two is the better one and why? I think I like the
>> second one more. The only problem is that it does not work. I get:
>> Error: /unmatchedmark in -->>--
>>
>> I am using:
>> GPL Ghostscript 9.06
>>
>
> You see that the name /color gets associated with the object mark,
> i. e. the --<<--, which is equivalent to --mark--, gets consumed and
> therefore is missing at the time -->>-- is executed.
>
> Think about it.
>
> Helge

I had been looking a little further. The << … >> combination is used
when assigning constants. I could use a roll, but my parameter list
does not always has the same length. So I will keep working in my old
way.

By the way: I read somewhere that the value before dict does not
matter. Is that true, or not?

A nice effect with this function: ;-)
    0 .25 3 {
        /count exch def
    
        40  40 40 count mul add
        40  40 4 count sub mul
        {1 count 10 div sub  0  0}
        ellipse
    
        200 40 count mul add  40
        40 4 count sub mul  40
        {0 count 4 div add  dup dup}
        ellipse
    } for

I like the grey better as the red.

-- 
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof

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What is the best way to work with a dictionary Cecil Westerhof <Cecil@decebal.nl> - 2013-07-13 22:13 +0200
  Re: What is the best way to work with a dictionary Helge Blischke <h.blischke@acm.org> - 2013-07-13 22:32 +0200
    Re: What is the best way to work with a dictionary Cecil Westerhof <Cecil@decebal.nl> - 2013-07-13 23:25 +0200
      Re: What is the best way to work with a dictionary luser- -droog <mijoryx@yahoo.com> - 2013-07-13 17:04 -0700
        Re: What is the best way to work with a dictionary Cecil Westerhof <Cecil@decebal.nl> - 2013-07-14 15:11 +0200
          Re: What is the best way to work with a dictionary luser- -droog <mijoryx@yahoo.com> - 2013-07-14 08:04 -0700
            Re: What is the best way to work with a dictionary Cecil Westerhof <Cecil@decebal.nl> - 2013-07-14 20:04 +0200
              Re: What is the best way to work with a dictionary Olle <olavi.sakari@gmail.com> - 2013-07-15 06:13 -0700
                Re: What is the best way to work with a dictionary Olle <olavi.sakari@gmail.com> - 2013-07-15 06:27 -0700

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