Support for scope-default transformer configuration

[krzemin]

This PR addresses #176. It's result of several prototyping rounds made in cooperation with @d12frosted.

More or less it implements the plan sketched here: #176 (comment)

TODO:

• more test cases, especially of newly added flags combinations
• provide analogous mechanism for patchers let's have it as a separate issue (Implicitly scoped patcher configurations #191)
• rethink naming and placement of newly added types
• update docs

[codecov]

Codecov Report

Merging #190 into master will increase coverage by 0.02%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #190      +/-   ##
==========================================
+ Coverage   99.34%   99.37%   +0.02%     
==========================================
  Files          20       21       +1     
  Lines         614      636      +22     
  Branches       62       61       -1     
==========================================
+ Hits          610      632      +22     
  Misses          4        4              

Impacted Files	Coverage Δ
...main/scala/io/scalaland/chimney/TransformerF.scala	100.00% <ø> (ø)
...a/io/scalaland/chimney/internal/macros/Model.scala	100.00% <ø> (ø)
...laland/chimney/internal/macros/PatcherMacros.scala	96.42% <ø> (ø)
.../main/scala/io/scalaland/chimney/Transformer.scala	100.00% <100.00%> (ø)
...main/scala/io/scalaland/chimney/dsl/FlagsDsl.scala	100.00% <100.00%> (ø)
...alaland/chimney/dsl/TransformerConfiguration.scala	100.00% <100.00%> (ø)
.../scalaland/chimney/dsl/TransformerDefinition.scala	100.00% <100.00%> (ø)
...scalaland/chimney/dsl/TransformerFDefinition.scala	100.00% <100.00%> (ø)
...la/io/scalaland/chimney/dsl/TransformerFInto.scala	100.00% <100.00%> (ø)
...ala/io/scalaland/chimney/dsl/TransformerInto.scala	100.00% <100.00%> (ø)
... and 7 more

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[d12frosted]

LGTM, next step would be to pass default flags from top to the very bottom 💯

Thank you for taking your time to try this idea.

[krzemin]

next step would be to pass default flags from top to the very bottom

@d12frosted it's already supported, see these test cases: https://github.com/scalalandio/chimney/pull/190/files#diff-8bf852c2438394dc69a2bd644c2a815eR1017 Or do you mean something else?

[d12frosted]

🤔 yeah, you are right. For some reason I was confused since I didn't see ability to pass configuration to Transformer.define. But looking at the tests - seems like it works 😸 thanks

[krzemin]

For some reason I was confused since I didn't see ability to pass configuration to Transformer.define.

Good point, let me elaborate.

Initially I thought that capturing implicit flags on Transformer.define and encoding them in the Transformer(F)Defnition would be a simple and clean idea. But to capture types passed by implicit instance, we would need third type parameter (for flags) and just calling it as Transformer.define[From, To] would not be possible any more.

I could fix it by making .define a whitebox macro and look for implicit inside, but... there is a simpler solution:

• build Transformer(F)Definition flags on top of TransformerFlags.Default
• require scoped flags only in .buildTransformer
• merge both flags stacks after capturing both types

It keeps almost the same semantics, but bring less troubles for the users.

[d12frosted]

@krzemin ah I see. This is something I didn't consider in my PRs. Nicely done!

[d12frosted]

This is wonderful! Thank you @krzemin 🎉

[krzemin]

Thank you for your efforts too @d12frosted!