Typed settings

[janezd]

Issue

Uses changes from biolab/orange-widget-base#62.

Changes in projections are given as an example of kinds of annotations that will be required from widgets to avoid warnings and allow storing their settings as json.

Includes

• Code changes
• Tests
• Documentation

[codecov]

Codecov Report

Merging #4721 (af8cbc4) into master (343f80b) will decrease coverage by 2.55%.
The diff coverage is 90.00%.

@@            Coverage Diff             @@
##           master    #4721      +/-   ##
==========================================
- Coverage   86.24%   83.68%   -2.56%     
==========================================
  Files         300      275      -25     
  Lines       61027    55609    -5418     
==========================================
- Hits        52634    46539    -6095     
- Misses       8393     9070     +677     

[janezd]

This migration is removed because annotated settings are no longer encoded into tuples. DomainContextHandler thus performs an exactly opposite migration for all annotated settings. If this migration here is left in, it would "unmigrate" the setting.

I assume such cases like this will be rare. So although this situation could be avoided if DomainContextHandler performed the migration after calling migrate_context, the downside would be that this would force the future migrate_context to work with raw, encoded settings instead of simpler, decoded, and thus force them to "understand" how coding is done - which should be of no concern to migrations.