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sot / ska_helpers

BSD 3-Clause "New" or "Revised" License
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Add ska_helpers.utils module with LazyDict #16

Closed taldcroft closed 3 years ago

taldcroft commented 4 years ago

Description

This adds a new module ska_helpers.utils as a generic drop box for Ska utilities that don't have a better home.

The first entry is the LazyDict class, which currently appears separately in Ska.engarchive and maude. This version is more complete/robust and somewhat tested.

This PR also converts the docstrings to numpydoc format.

Testing

javierggt commented 4 years ago

This smells like collections.defaultdict.

In what way is it different?

javierggt commented 4 years ago

ah, never mind. I see the difference.

taldcroft commented 3 years ago

@javierggt - I'm also not a fan of the .get() syntax, but I don't see a way around it.

My first thought for this task was also the module level __getattr__ and indeed I was excited to use this new feature. However, __getattr__ only works for attribute access from outside the module itself. So my_module.lazy_attribute works, but within my_module trying to access lazy_attribute just gives a NameError.

If you can find a way to make this work then that would be great, though there are some other issues with __getattr__ in this context. The main is that in any module that wants to use lazy values then a __getattr__ function needs to be defined by the user module to use those lazy values. It isn't obvious there is a nice way to handle this, especially if the user module is independently defining __getattr__ for another reason.

I used LazyVal here: https://github.com/sot/chandra_aca/pull/108/files#diff-21392387835d093a39ee20461a8c92f248b70ac2a69150f23ffbf4c7a7f15860R29

taldcroft commented 3 years ago

@javierggt @jeanconn - I think I have addressed all the review comments.