#94 - TransformerTrait: allow a list syntax for the transformers option

[njoubert-cleverage]

Description

Fixes #94.

The transformers option of TransformerTrait (TransformerTask, MappingTransformer, ArrayMapTransformer, CachedTransformer, RulesTransformer, generic transformers) also accepts a list, to chain the same transformer without # suffix. Each item is either:

• a transformer code without options: - trim
• a map with a single code: options entry: - callback: { callback: array_filter }

transformers:
  - trim
  - callback:
      callback: array_filter
  - callback:
      callback: array_reverse

• Any other item (integer, empty string, map with several codes...) throws an InvalidArgumentException with its position.
• In a TransformerException message, a listed transformer is identified by its code followed by # and its position (Transformation 'callback#1' have failed).
• The map syntax (with # suffixes) is still supported and is not deprecated.

A list was not accepted before (integer keys failed with a TypeError), so this is a pure addition.

Checked end-to-end in process-bundle-demo with a demo.transformer_list process (list in a TransformerTask, in the transformers of a mapped property, and in a generic transformer declared in YAML).

Requirements

• Documentation updates
  • Reference
  • Cookbooks
  • Changelog
• Unit tests

Breaking changes

None.

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