[Python-Dev] Simple generators, round 2

[Jeremy Hylton]

>>>>> "TP" == Tim Peters <tim.one@home.com> writes:

  >> I'm not sure about Jython.  The sys._getframe(), frame.suspend(),
  >> and frame.resume() low level interface is nice.  I think Jython
  >> must know which frames are going to be suspended at compile time.

  TP> Yes, Samuele said as much.  My belief is that generators don't
  TP> become *truly* pleasant unless "yield" ("suspend"; whatever) is
  TP> made a new statement type.  Then Jython knows exactly where
  TP> yields can occur.  As in CLU (but not Icon), it would also be
  TP> fine by me if routines *used* as generators also needed to be
  TP> explicitly marked as such (this is a non-issue in Icon because
  TP> *every* Icon expression "is a generator" -- there is no other
  TP> kind of procedure there).

If "yield" is a keyword, then any function that uses yield is a
generator.  With this policy, it's straightforward to determine which
functions are generators at compile time.  It's also Pythonic:
Assignment to a name denotes local scope; use of yield denotes
generator. 

Jeremy