[texhax] "@" : vowel or glottal stop ? (was : Some puzzling TeX)

[Heiko Oberdiek]

On Sat, Feb 19, 2011 at 12:12:03PM +0000, Philip Taylor (Webmaster, Ret'd) wrote:

> Uwe Lueck wrote:
> >
> > "Philip Taylor (Webmaster, Ret'd)"<P.Taylor at rhul.ac.uk>  wrote 19.02.2011 11:37:16:
> >> I have never understood (and continue to fail to understand)
> >> why, when Don made it quite clear in Plain.TeX that "@" is a
> >> vowel,
> >
> > where? how? How are \thr@@, \count@, \prim at s, \pr at m@s, \pr@@@s pronounced?
> 
> \thr@@  : three

plain.tex:
| \chardef\@ne=1
| \chardef\tw@=2
| \chardef\thr@@=3
| \chardef\sixt@@n=16

* Why \thr@@ and \sixt@@n have *two* "@"?
* \@ne has the "@" at the beginning, not at the end as the others.

> \count@ : count zero

plain.tex:
| \countdef\count@=255
but
| \dimendef\dimen@=0
| \dimendef\dimen at i=1 % global only
| \dimendef\dimen at ii=2

Thus "@" could also be interpreted as separator for the
name and the roman numeral:
  \def\DefineMyDimen#1{%
    \expandafter\dimendef
    \csname dimen@\romannumeral#1\endcsname = #1 %
  }
  \DefineMyDimen{0}
  \DefineMyDimen{1}
  \DefineMyDimen{2}

Yours sincerely
  Heiko Oberdiek