Re: [Groff] A nut to crack

[Werner LEMBERG]

> Finally I got a `problems' file. The suicidal trap seems to work
> like this:

[...]  I have to apologize for pointing you to an overly complex
example.  Normally it isn't necessary at all to rename `.wh'.  Here a
simple example:

  .de kamikaze-trap
  .  wh \\n[nl]
  .  nop We are in a kamikaze trap!
  ..
  .
  .wh 5i kamikaze-trap

> It seems that yes, wh_saved can invoke the macro in question, but it
> seems that saving/restoring wh does not eliminate the trap, .ptr
> still shows it.

>From groff.info:

  -- Request: .ptr
      Print the names and positions of all traps (not including input
      line traps and diversion traps) on `stderr'.  Empty slots in the
      page trap list are printed as well, because they can affect the
      priority of subsequently planted traps.

Renaming .wh doesn't influence the list of traps -- the macro has just
a different name.

> Btw, wouldn't it be less work to introduce a kamikaze trap into
> groff than working with such constructs at document level many times
> over?  What do you think?

I think the above example is simple enough -- you need a single line
to remove the trap which is currently executed.


    Werner