GNU Info

(m4.info)Cleardiv

---

Prev: Divnum Up: Diversions

---

Enter node , (file) or (file)node

Discarding diverted text
========================

   Often it is not known, when output is diverted, whether the diverted
text is actually needed.  Since all non-empty diversion are brought back
on the main output stream when the end of input is seen, a method of
discarding a diversion is needed.  If all diversions should be
discarded, the easiest is to end the input to `m4' with `divert(-1)'
followed by an explicit `undivert':

     divert(1)
     Diversion one: divnum
     divert(2)
     Diversion two: divnum
     divert(-1)
     undivert
     ^D

No output is produced at all.

   Clearing selected diversions can be done with the following macro:

     define(`cleardivert',
     `pushdef(`_num', divnum)divert(-1)undivert($@)divert(_num)popdef(`_num')')
     =>

   It is called just like `undivert', but the effect is to clear the
diversions, given by the arguments.  (This macro has a nasty bug!  You
should try to see if you can find it and correct it.)