The problem with that construct is that trueaction itself must evaluate to true, or the expression will evaluate to falseaction, which most likely is not what you want:

  >>> 0 if 1 else 2
  0
  >>> 1 and 0 or 2
  2

Even crazier things can happen if trueaction has side effects:

  >>> def trueaction():
  ...     print 'trueaction called'
  ...     return 0
  ...
  >>> def falseaction():
  ...     print 'falseaction called'
  ...     return 'hello'
  ...
  >>> True and trueaction() or falseaction()
  trueaction called
  falseaction called
  'hello'
  >>> trueaction() if True else falseaction()
  trueaction called
  0