# [pdftex] removal of some extensions -- yes or no?

Thanh Han The hanthethanh at gmail.com
Thu Nov 23 09:02:22 CET 2006

```On Wed, Nov 22, 2006 at 04:07:42PM +0100, Christoph Bier wrote:
> Thanh Han The schrieb am 22.11.2006 11:24:
>
> > Dear list,
> >
> > I am considering to remove some extensions I added to pdftex
> > recently, as it's hard to make them work reliably, and they
> > also seem little useful. In short they are:
> >
> > ,--------
> > | \pdfadjustinterwordglue, \knbscode, \stbscode, \shbscode:
> > | adjust the interglue space according to the charater before
> > | the glue
> > |
> > | \pdfprependkern, \knbccode: auto-insertion of a kern before a char
> > |
> > | \pdfappendkern, \knaccode: auto-insertion of a kern after a char
> > `--------
> >
> > Before I make a decision, I would like to listen to other
> > opinions. So please let me know what you think of this.
>
> CMIIW but I thought \pdfprependkern and \pdfappendkern would provide
> an opportunity to addjust the tracking without changing the font's
> kerning itself. I'd really appreciate this extension because
> changing a font is hard work (and needs a lot of knowledge) but
> tracking adjustment is often necessary.

yes it is handy to modify fonts and related things
on-the-fly. However the font mechanism in tex is connected
to too many things (kerning, ligature, hyphenation, etc.),
so it's very easy to break things. I think a better place to
experiment with such thing is luatex when it is ready, or
some re-implementation of tex like ant/nts/extex. Having
those features in pdftex has 2 disadvantages:

- it's unlikely that I am able to make them work properly
with pdftex
- stability is now important for pdftex

Best regards,
Thanh
```