[feat] Enable self.log in callbacks

[tchaton]

What does this PR do?

This PR enables user to call self.log directly from the callbacks and not pl_module.log.

Fixes # (issue)

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[pep8speaks]

Hello @tchaton! Thanks for updating this PR.

There are currently no PEP 8 issues detected in this Pull Request. Cheers! 🍻

Comment last updated at 2020-12-14 07:15:11 UTC

[codecov]

Codecov Report

Merging #5094 (8a76bbc) into release/1.2-dev (16feb51) will decrease coverage by 1%.
The diff coverage is 100%.

@@               Coverage Diff                @@
##           release/1.2-dev   #5094    +/-   ##
================================================
- Coverage               93%     92%    -1%     
================================================
  Files                  134     134            
  Lines                 9907   10023   +116     
================================================
+ Hits                  9205    9250    +45     
- Misses                 702     773    +71     

[mergify]

This pull request is now in conflict... :(

[SkafteNicki]

Question: should we also allow for callbacks to write predictions aka self.write_prediction and self.write_prediction_dict?

[tchaton]

Yes, but within another PR :)

[awaelchli]

This PR breaks some of my callbacks.
I advise against dynamically binding methods like this. This will be extremely difficult to debug, both on the side of the user and on the side of the developer. I am convinced this is not future-proof.
If it really has to be like this, can we at least add an empty stub to the callback class, so that there is at least some indication for a name clash?

[indigoviolet]

@tchaton please consider adding the stub as above. this also upsets mypy.

[KeAWang]

Any plans to revert this?