Lazy import

[ericpre]

This PR will need hyperspy/hyperspy#3569 to be release and I opened it to try if hyperspy/hyperspy#3569 works well.

All signals import are now ~0.3s.

Progress of the PR

• Implement lazy import using lazy-loader,
• refactor exspy.utils to avoid import redirection,
• [n/a] docstring updated (if appropriate),
• [n/a] update user guide (if appropriate),
• update tests,
• add a changelog entry in the upcoming_changes folder (see upcoming_changes/README.rst),
• Check formatting of the changelog entry (and eventual user guide changes) in the docs/readthedocs.org:exspy build of this PR (link in github checks)
• ready for review.

[codecov]

Codecov Report

❌ Patch coverage is 83.93178% with 358 lines in your changes missing coverage. Please review.
✅ Project coverage is 88.33%. Comparing base (1e33c62) to head (341ecd1).
⚠️ Report is 19 commits behind head on main.

Files with missing lines	Patch %	Lines
exspy/signals/_eels.py	77.77%	102 Missing and 54 partials ⚠️
exspy/signals/_eds.py	86.26%	27 Missing and 26 partials ⚠️
exspy/signals/_eds_tem.py	81.72%	28 Missing and 25 partials ⚠️
exspy/signals/_eds_sem.py	59.79%	30 Missing and 9 partials ⚠️
exspy/utils/eels/dielectric.py	70.73%	8 Missing and 4 partials ⚠️
exspy/utils/eds/_xray_lines.py	93.16%	5 Missing and 3 partials ⚠️
exspy/utils/eds/_quantification.py	93.91%	3 Missing and 4 partials ⚠️
exspy/_misc/eels/tools.py	0.00%	5 Missing ⚠️
exspy/signals/_dielectric_function.py	84.84%	3 Missing and 2 partials ⚠️
exspy/utils/eds/_particle_matter_interaction.py	81.25%	1 Missing and 2 partials ⚠️
... and 13 more

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #160      +/-   ##
==========================================
- Coverage   88.86%   88.33%   -0.54%     
==========================================
  Files          79      100      +21     
  Lines        7652     7764     +112     
  Branches      910      932      +22     
==========================================
+ Hits         6800     6858      +58     
- Misses        578      632      +54     
  Partials      274      274              

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[ericpre]

@jlaehne, @CSSFrancis, would you be able to review this PR?

[ericpre]

Checking the integration test suite, I added back the signals submodules (for example, exspy.signals.eels) because it is used in atomap and hy - even if following the API reference, it should be imported from exspy.signals and not their submodules.

The remaining failure (hyperspy_gui_ipywidgets) is fixed in hyperspy/hyperspy_gui_ipywidgets#96.

[jlaehne]

The remaining failure (hyperspy_gui_ipywidgets) is fixed in hyperspy/hyperspy_gui_ipywidgets#96.

I merged the corresponding PR. LGTM if the tests pass, @CSSFrancis do you want to have another quick look?

[ericpre]

@CSSFrancis, in case, you want to have a look, this is a large PR, but I think that it worth checking is the API reference: https://exspy--160.org.readthedocs.build/en/160/reference/index.html and privatized imports. The integration test suite passed except that hyperspy_gui_ipywidgets needs a release to include hyperspy/hyperspy_gui_ipywidgets#96.

The rest is moving import around to defer import, etc. and implementing lazy loading using lazy_loader.