[Dev-luatex] Modifying the LuaTeX Engine

Idris Samawi Hamid ادريس سماوي ح Idris Samawi Hamid ادريس سماوي ح
Fri Dec 26 04:31:58 CET 2008

On Thu, 25 Dec 2008 19:53:00 -0700, وفا خلیقی، Vafa Khalighi  
<vafa at live.com.au> wrote:

>> I'm just curious: Did Yazdipur try to communicate with the Omega
>> developers and offer patches etc?
> I
> do not think so, It seems that he has got no interest in the Unicode
> world and he is a big fan of Knuth's TeX engine only and does not want
> to write codes for PDFTeX, XeTeX and LuaTeX.

Hmm, if that is true then it is not very promising...

>> Have you tested the bidi in luatex and compared it with that of
>> TeX-e-Parsi? It is already much better than etex's.
> Yes, I did and I still think TeX-e-Parsi's bidirectional algorithm is  
> more powerful than LuaTeX's.

Ok, but how do you qualitatively and/or quantitatively justify that?

> As I said Yazdipour has faith only in Donald Knuth
> and his work and no interest in other TeX engines, that is what I have
> heard. Donald Knuth himself congratulated him for writing the
> TeX-e-Parsi's engine.

Again, I think that Yazdipour's approach here is anachronistic -- with all  
due respect. But if this is indeed the case, then this tells me that there  
is no Omega code in TeX-e-Parsi at all. So in effect you are asking that  
luatex ditch the entire bidi model it has and replace it with  
TeX-e-Parsi's. Then we have to hook that in to pdf output and many other  
things. Given the stability and polish of the bidi engine as it stands I  
am not sure this is wise at the moment

>> 1. Make an exhaustive test suite that compares bidi behavior in luatex
>> with that of TeX-e-Parsi. You don't need to use any arabic-script, just
>> latin modern samples;
> I
> absolutely agree. But Let's have a test file. I write that test file
> with TeX-e-Parsi and you write the test file with LuaTeX and then we
> compare the results. If you can send a sample/test file so then I can
> typeset in with TeX-e-Parsi.

Hmm: You should create and run your test file -- which should contain a  
variety of individual torture tests -- with both luatex and TeX-e-Parsi.  
Compare the pdf's and identify the differences. Write a report and submit  
it to Hans, Taco, and me.

I have attached two test files from almost exactly one year ago. You can  
modify these to your liking and see what happens. But I suspect you'll  
want to create your own tests from scratch.

The apparent verbatim bug is there, on the first page of global_rl2.pdf,  
but other than that bidi is quite solid.

Taco: Interestingly, running the file today results in a bug, but a year  
ago it showed up in the last two lines whereas now it only shows up in the  
last line on page 1.

>> 2. Identify the diffferences between the two and determine which -- if
>> either -- has the saner behavior for each case;
> Agree.
> It might turns out that TeX-e-Parsi is powerful in some areas and
> LuaTeX in other areas. So we just can look at the powerful areas of
> bidirectional typesetting.


Best wishes

Professor Idris Samawi Hamid, Editor-in-Chief
International Journal of Shi`i Studies
Department of Philosophy
Colorado State University
Fort Collins, CO 80523
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