Python ''.format(): "tuple index out of range"?

Question

Consider the following snippet:

>>> def foo(port, out, udp=False, ipv6=False, data=''):
...     if not data:
...             data = 'foo {family} {:port} {direction}'.format(
...                             family=('ipv6' if ipv6 else 'ipv4'),
...                             port=port,
...                             direction=('out' if out else 'in'))
...     return data
...
>>> foo(12345, out=True)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 6, in foo
IndexError: tuple index out of range

As far as I know, the scoping of names look alright. What's with the cryptic error?

Nevermind. {:port} should be {port:}.

Santa
– Santa

2010-09-16 00:10:19 +00:00
Commented Sep 16, 2010 at 0:10 — Santa
– Santa, Commented Sep 16, 2010 at 0:10

Tim McNamara · Accepted Answer · 2010-09-16 19:35:43Z

2

Watch the colon. Move it from the front of the port area:

Either

data = 'foo {family} {port:} {direction}'.format(

Or

data = 'foo {family} :{port} {direction}'.format(

The results of the two options are:

>>> foo(12345, out=True)
'foo ipv4 12345 out'
>>> foo(12345, out=True)
'foo ipv4 :12345 out'

edited Sep 16, 2010 at 19:35

answered Sep 16, 2010 at 0:07

Tim McNamara

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2 Comments

Santa Over a year ago

Noted. <pedantic>They're called "colons"</pedantic>. ;-)

Tim McNamara Over a year ago

That's not pedantic at all :) Remedied.

Santa · Accepted Answer · 2010-09-16 00:10:50Z

0

{:port} should be {port:}.

answered Sep 16, 2010 at 0:10

Santa

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