On 2007-09-25, Mark Summerfield <[EMAIL PROTECTED]> wrote:
> If there is positive feedback I will submit the PEP to the reviewers,
> so if you think it is a good idea please say so. (I'm sure that if you
> _don't_ like it you'll tell me anyway:-)
I like the idea, ie +1.
> This PEP proposes the addition of a sorted dictionary class to the
> standard library's collections module.
You don't seem to mention the sort criterium. I'd suggest to use the __lt__
operator, which you probably intended since it is commonly used.
Also, can I specify a custom sort function, as with list.sort() ?
> In addition, the keys() method has two optional arguments:
>
> keys(firstindex : int = None, secondindex : int = None) -> list of
Not sure this is a good idea. Wouldn't simply
mysorteddict.keys()[firstindex:secondindex]
be much better? It can do all you propose, and more (with iterators/generators
and such). I see no need to implement it inside the sorteddict as well.
> Since the sorteddict's data is always kept in key order, indexes
> (integer offsets) into the sorteddict make sense. Five additional
> methods are proposed to take advantage of this:
>
> key(index : int) -> value
>
> item(index : int) -> (key, value)
>
> value(index : int) -> key
>
> set_value(index : int, value)
>
> delete(index : int)
I wouldn't do this. It breaks compability with the normal dict. A beginning
user will expect dict and sorteddict to behave the same (except for
sortedness), including their set of supporting functions imho.
Otherwise, please make a case for them (and maybe even a new PEP to get them in
both types of dicts).
> Examples
>
> To keep a collection of filenames on a case-insensitive file
> system in
> sorted order, we could use code like this:
>
> files = collections.sorteddict.sorteddict()
> for name in os.listdir("."):
> files[name.lower()] = name
The more interesting case would be to you preserve case of the files within the
keys.
I usually need this data structure with an A* algorithm implementation, where I
need to obtain the cheapest solution found so far.
> for item in listOfItems:
> itemsByDate["%s\t%17X" % (item.date, id(item))] = item
> itemsByName["%s\t%17X" % (item.name, id(item))] = item
> itemsBySize["%s\t%17X" % (item.size, id(item))] = item
Wouldn't a line like "itemsBySize[(item.size, id(item))] = item" do as well?
(or with a custom sort function on items?)
> Now we can iterate in date or name order, for example:
>
> for item in itemsByDate:
> print item.name, item.date
Hmm, not with dict:
>>> for x in {1:10, 2:20}:
... print x
...
1
2
So you should get your "%s\t%17X" strings here.
Sincerely,
Albert
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