Documentation for iteration in mappings

[Dennis Benzinger]

Hi!

I must be blind because I didn't find anything in the documentation
which says iterating over an dictionary iterates over its keys.

For example

a_dictionary = {0: "zero", 1: "one"}
for x in a:
print x

gives you

0
1

Where is this information hidden?

Bye,
Dennis

 

[=?ISO-8859-15?Q?Michael_Str=F6der?=]

I must be blind because I didn't find anything in the documentation
which says iterating over an dictionary iterates over its keys.

For example

a_dictionary = {0: "zero", 1: "one"}
for x in a:
print x

gives you

0
1

Where is this information hidden?

You should examine your program. Simply pasting the code above to the
Python shell fails as expected:

$ python
Python 2.4.2 (#1, Oct 1 2005, 14:32:09)
[GCC 3.3.5 20050117 (prerelease) (SUSE Linux)] on linux2
Type "help", "copyright", "credits" or "license" for more information..... print x
....
Traceback (most recent call last):

Ciao, Michael.

 

[Steven D'Aprano]

I must be blind because I didn't find anything in the documentation
which says iterating over an dictionary iterates over its keys. [snip]
Where is this information hidden?

You should examine your program. Simply pasting the code above to the
Python shell fails as expected:

Yes, this is true, but also irrelevant. The question isn't about the code,
but about the documentation.

The answer does appear to be hidden quite deeply. I had to dig out an old
"What's New" for version 2.2 to find it, hidden away in a section on
iterators:

http://aspn.activestate.com/ASPN/do...w/2.2/index.html#SECTION000400000000000000000