Re: [Groff] An environment variable for enabling compatibility mode

[ralph]

Hi Jon,

> > Back in the `Surprise, Surprise' thread I raised the issue of a
> > single compatibility flag being insufficient.
> > 
> >     http://www.ffii.org/archive/mails/groff/2001/Aug/0085.html
> 
> IIRC, I was not entirely convinced by your arguments in that thread.

No, Werner asked me for a good example and his email drifted down my
inbox until it finally fell out the bottom.

> We clearly need some method of improving existing groff functions
> while maintaining compatibility for existing documents and scripts.

Right.  Given groff version N can break groff version N-1 documents
there's a need.  Just like in software CM you capture all the
compilation environment as well as the source code for a version.

I guess groff could say that a book author has to do the same thing,
i.e. if they know groff 1.16 formats their book OK then they keep 1.16
around for their book.

> Having to specify (potentially) dozens of options is not too
> attractive, but as far as I can see, anything else causes
> compatibility problems.

I think groff could install a installation-wide compat. flags file
that just enables all enhancements by default.

> I believe we need very fine granularity (i.e. we need to be able to
> enable/disable a particular functionality).  If we just have a switch
> to enable the foobar set of options we run into the problem of
> someone needing some but not all of the foobar options.

I agree about the fine granularity, but I guess there could be aliases
for sets, e.g. `all'.

Cheers,


Ralph.