Re: [Groff] [groff] mission statement 3

[Ralph Corderoy]

Hi,

Doug wrote:
> There is one property of TeX (and HTML) that's worth emulating:
> recursive nesting.  It's a challenge to the preprocessor model (eqn,
> tbl, pic), but one that deserves serious consideration.  How about
> letting "preprocessors" be called by piping segments out and back, not
> only by piping in?  (This is a standard facility of the sam editor.
> The line breaks in this email were set by piping out to fmt.)

vi(1) offers something similar with its ! command, e.g. !}fmt runs the
lines from here to the end of the paragraph -- } -- through fmt with the
output replacing the input.

Taking just one example, sometimes a tbl cell will want to constrain the
pic within it, other times be basing its size on the pic.  In both cases
the .PS/.PE will be within the T{...T}.  Can a crude workaround within a
linear pipeline be done with different .PS/.PE pairs being used and
extra commands in the pipeline switching them live as the ones pic looks
at this time?

    ... | switch +PS2 | pic | switch -PS2 +PS1 | tbl | pic | ...

Cheers, Ralph.