Generate only one instance for `MongoDownloader`

dachengx commented 2 weeks ago

Before you submit this PR: make sure to put all operations-related information in a wiki-note, a PR should be about code and is publicly accessible

What does the code in this PR do / what does it improve?

Similar to https://github.com/XENONnT/straxen/pull/1397 but in another approach. When trying downloader = straxen.MongoDownloader(), unless *args or **kwargs changed for MongoDownloader, return the already existed instance of MongoDownloader.

Can you briefly describe how it works?

Can you give a minimal working example (or illustrate with a figure)?

Please include the following if applicable:

[ ] Update the docstring(s)
[ ] Update the documentation
[ ] Tests to check the (new) code is working as desired.
[ ] Does it solve one of the open issues on github?

Notes on testing

Until the automated tests pass, please mark the PR as a draft.
On the XENONnT fork we test with database access, on private forks there is no database access for security considerations.

All italic comments can be removed from this template.

coveralls commented 2 weeks ago

coverage: 91.083% (-0.07%) from 91.154% when pulling 729eb9cd5e188b5251eb304dac91b792982e2041 on mongo_downloader_2 into 7a4edcebac5b6fc165b71de79ae19ede6e7a52d6 on master.

coveralls commented 2 weeks ago

coverage: 91.161% (+0.007%) from 91.154% when pulling 729eb9cd5e188b5251eb304dac91b792982e2041 on mongo_downloader_2 into 7a4edcebac5b6fc165b71de79ae19ede6e7a52d6 on master.

XENONnT / straxen