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Re: Union Type Object problem

From: Hans Aberg
Subject: Re: Union Type Object problem
Date: Wed, 11 Aug 2004 18:43:33 +0200

At 22:21 +0200 2004/08/10, Laurence Finston wrote:
>> If your actions are such that each rule in effect is statically typed, then
>> you probably do not need dynamic_cast, and you can static_cast everything
>> back and forth to void*.
>I didn't do this on purpose, it just worked out this way.

And on the same token (no pun intended), I started off with a polymorphic
program, and successively expanded it, as well as a fairly independent
parser. So I just used the polymorphic approach because it is natural in my
context. I will think more about the static_cast approach in the future.

>  In a way, I haven't
>really designed the 3DLDF language myself, it's based on Knuth's Metafont
>language.  There are differences because of the differences between 2D and 3D
>and because font design doesn't require the same kinds of basic geometric
>types that 3D graphics does.  Nor has it  been possible for me to implement
>certain things in Bison that Knuth does with his hand-written parser code,
>although I don't claim that it's impossible in principle.

In discussion in the LaTeX3 project list
<address@hidden>, one said that Don shunned parser
generators and grammars when he did the TeX stuff. So, therefore TeX is as
it is, and it may difficult to use a parser generator to do a program that
exactly duplicates the original TeX-cluster of programs.

> I'm also not as
>clever as Knuth.

So it is more a question of that it follows his own peculiar ways, which
are hard to duplicate, rather than the question of being smart. :-)

  Hans Aberg

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