[Python-Dev] LinkedHashSet/LinkedHashMap equivalents

["Martin v. Löwis"]

John Williams wrote:
> The other use case I have is for dealing with data where the iteration 
> order doesn't matter to the program but it does matter to users.  For 
> instance, consider the ConfigParser's write method.  Any ordering of 
> values in the output is functionally equivalent, but the original data 
> is likely to have come from a file that was arranged in some meaningful 
> order, and it would be nice to preserve that order, especially if it can 
> be done with no extra effort.

That is a good example, IMO. But then, in the specific case, the
dictionary for each section is created deeply inside ConfigParser,
with the lines

                         cursect = {'__name__': sectname}
                         self._sections[sectname] = cursect

So this uses a builtin dict, and there is no easy way to override it
for the application.

Of course, given your reasoning, ConfigParser *should* use an
OrderedDictionary (probably both for cursect and for self._sections),
in which case this would all be transparent to the application.

Regards,
Martin