Dict/List manipulation from C

[Bernhard Herzog]

"Richard Harvey" <tririch at connect.net> writes:

> (1) Replacing the contents of one dictionary with the contents of another.
> This is the case when I pass a dictionary from Python to my C code, using
> the dictionary as a "keyed" structure.  Through other subsequent calls I
> create a new dictionary with matching entries, and want to return this back
> to the caller.  Right now I'm having to retrieve the (key,value) list, then
> loop through each entry in the passed dictionary calling SetItem(key,value).

You could also use PyDict_Next. Unfortunately this function appears to
be undocumented.

> Seems a bit of overkill when in Python itself I can just say dict1 = dict2.

But dict1 = dict2 doesn't copy the dictionary. It just rebinds the dict1
variable. In C that would be

Py_DECREF(dict1);
dict1 = dict2;
Py_INCREF(dict1);

The refcounting may have to be different in your code, of course.

> (2) Removing all entries from a list.

PySequence_DelSlice(list, 0, PySequence_Length(list))

should do it, I think.

-- 
Bernhard Herzog   | Sketch, a drawing program for Unix
herzog at online.de  | http://sketch.sourceforge.net/