(m4.info.gz) Cleardiv

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(m4.info.gz) Divnum

(m4.info.gz) Diversions

 
 9.4 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:
 
  -- Composite: cleardivert ([DIVERSION]...)
      Discard the contents of each listed diversion.
 
      define(`cleardivert',
      `pushdef(`_n', divnum)divert(`-1')undivert($@)divert(_n)popdef(`_n')')
      =>
 
    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.   Answers)
 

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(m4.info.gz) Divnum

(m4.info.gz) Diversions