dry-auto_inject

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To me it happened that I accidentally injected my dependencies into a namespace module instead of into a class, like this:

module Operations
  module Articles
    include Import["repositories.articles"]

    class Create
      # ...
    end
  end
end

When I did that, I got an error originating from that line, but happening somewhere in dry-auto_inject's internals (a NoMethodError for NilClass). This led me to believe that I've somehow incorrectly passed parameters to Import[], and it took me a while to realize what was the error.

The error occurred because the downstream code assumes the #initialize method will be defined, which is not the case for modules. To improve the developer experience, we detect that we're attempting to inject into a module and raise an explicit exception.

I won't go into details right now, but I want to note that this is strategy-dependent. For example, effect-based DI works with modules or whatever. And I believe we can make built-in strategies to work with modules too. However, this would require some hacking.

Hmm, you're right, I haven't considered that. I've also often seen people using modules instead of classes for stateless operations, in which case they might want to use auto-inject.

I'll keep this open in case you still want to merge it until support for modules is added.

Here is an overview of what got changed by this pull request:

Issues
======
- Added 3
           

Complexity increasing per file
==============================
- lib/dry/auto_inject/strategies/constructor.rb  2
         

Clones added
============
- spec/dry/auto_inject_spec.rb  3
         

See the complete overview on Codacy