Confusing behavior when using star globs and list indexing

[igordertigor]

When using dpath.util.search retrieves an empty list, it won't include it in the result:

>>> import dpath.util
>>> a = {'a': {'b': []}}
>>> b = {'a': {'b': [1, 2, 3]}}
>>> dpath.util.search(a, 'a/b/*')  # expecting {'a': {'b': []}} here
{}
>>> dpath.util.search(b, 'a/b/*', afilter=x > 3 if isinstance(x, int) else True)   # should again give {'a': {'b': []}}
{}
>>> dpath.util.search(a, 'a/b')
{'a': {'b': []}}

I find this behaviour counterintuitive: I tend to "pronounce" the star as "give me all items in this location". Hence if the item is an empty list, then I want that empty list. Am I misunderstanding something here? What would be the expected behaviour? Also, the final call illustrates something that I find particularly strange here: I would think of both globs to give the same results, but they don't seem to do so.

A second confusing thing seems to be the handling of numeric indexes for lists:

>>> dpath.util.search(b, 'a/b/0')
{'a': {'b': [1]}}
>>> dpath.util.search(b, 'a/b/-1')  # expecting {'a': {'b': [3]}} here.
{}

How would I pass negative indexes? Is that supported at all?

[moomoohk]

Hi @igordertigor,
Negative indexing is not supported at the moment. I am currently experimenting with this feature on #171.

I will also investigate the first issue you mentioned with the stars.

Regards

[moomoohk]

@igordertigor
Please review the changes on #172 which add support for negative number indexing.

I've started investigating the other issue and it seems to be more problematic. I'm not sure I will be able to resolve it. Follow #173 for updates on that.

[moomoohk]

Negative index suggestion also appears in #138.

[igordertigor]

Thanks @moomoohk for looking into that. I didn't comment on #172 because it was already merged. Regarding #173, I'm not entirely sure if I understand what exactly the issue is. But that might be my limited insight into dpath's internals.

[moomoohk]

Sorry the issue closed automatically. I'm reopening until the second issue is resolved.