New (?) suggestion re: 'while x = f(): ...'

[Jeff Epler]

On Wed, May 29, 2002 at 09:10:59AM +0000, Duncan Booth wrote:
> Jeff Epler <jepler at unpythonic.net> wrote in 
> news:mailman.1022619227.16027.python-list at python.org:
> 
> > and instead of
> >     while 1:
> >      x = f()
> >      if not x: break
> >      ...
> > you can write
> >     for x in H(f):
> >      ...
> > 
> > Given suitable names for G() and H() (and I haven't thought of any yet)
> > does anybody favor this over the "pythonic" syntax?  Personally, I think
> > I'll stick to doing it in the old-fashioned way, but I wanted to share
> > my idea with the world...
> 
> 'H' is spelled 'iter' and already exists.

Not quite -- H will stop on "any false value", while iter(f, "") will
stop on a single value.

Now, if iter would take a function as a second argument...

    def myiter(f, g):
	if callable(g):
	    while 1:
		v = f()
		if g(v): break
		yield v
	else:
	    while 1:
		v = f()
		if v==g: break
		yield v
then myiter(f, lambda x: not x) would be the equivalen of H(f).

Jeff