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Newsgroups: comp.lang.python
Date: Thu, 8 Dec 2011 07:42:46 -0800 (PST)
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Xref: x330-a1.tempe.blueboxinc.net comp.lang.python:16841

On Thursday, December 8, 2011 10:16:56 AM UTC-5, Heiko Wundram wrote:
> Am 08.12.2011 15:47, schrieb Robert Kern:
> > Would including the respective numbers help your thought processes?
> > ValueError: too many values to unpack (expected 2, got 3)
>=20
> Not possible in the general case (as the right-hand side might be an=20
> arbitrary iterable/iterator...).

Why not?  Take this example:

def i():
    i =3D 0
    while True:
        print "returning:", i
        yield i
        i +=3D 1

a, b =3D i()

./iter.py
returning: 0
returning: 1
returning: 2
Traceback (most recent call last):
  File "./iter.py", line 10, in <module>
    a, b =3D i()
ValueError: too many values to unpack

The exception was raised when i() returned it's third value, so saying "exp=
ected 2, got 3" is exactly correct.  Yes, it is true that it might have got=
ten more if it kept going, but that's immaterial; the fact that it got to 3=
 is what caused the Holy Hand Grenade to be thrown.