[tex-eplain] Hyperlinks in Eplain

[geolsoft at mail.ru]

On Thu, Jul 21, 2005 at 02:44:02PM -0400, Karl Berry wrote:
>     I think so but never actually tried it.
> 
> Can you try it?  It would be good to know the real story so we can put
> it into the manual.

I will, as I will try to add the `dvips' driver.  I will
send the patch (if successful) and describe my experience.

> I was talking about the case where the user does not request a
> particular driver at all.  In that case, I think we should use pdftex
> \ifpdf, and dvipdfm if not.
> 
> I'm not sure if your code allows using this stuff without specifying a
> driver (sorry, I haven't had a chance to actually look at it), but if it
> doesn't, that would be a good feature.

Sorry, it was me misunderstanding you.  I see now what you
mean.  Unfortunately the code does not currently allow this.
This could be arranged, of course:  the user would have to
define \hldriver to the driver they want before including
eplain.tex.  When eplain.tex gets into control, if \hldriver
is undefined we could default to pdftex/dvipdfm.

This has two drawbacks:

 1) Precompiled formats will only be possible for a single
    driver, the one that was selected at the time of \dump.

 2) I wanted `out-of-box' eplain to remain as close to the
    original eplain as possible, to minimize surprises when
    recompiling old documents.  The above approach may have
    grave consequences for old documents, as bad as failure
    to compile and/or altered typesetting (whichever is
    worse).  There are many reasons.  One example:  in the
    original eplain it was perfectly legal to start the
    paragraph by saying `\xref{LABEL}'; with pdftex driver,
    however, this will give you the following error:

! pdfTeX error (ext1): \pdfstartlink cannot be used in vertical mode.

    This could be cured by \leavevmode at the beginning of
    \hlstart, but in case of dvipdfm a link can actually
    start in vertical mode (I am addressing this issue in
    another thread right now).  There are still other
    possible glitches (boxes that \pdfdest's are placed
    inside to have them raised, \special's for links and
    destinations, probably something else).

If you still think it worth to have a default driver, I
could arrange it.

-- 
Best regards,
Oleg Katsitadze