Raise exception when injecting into modules - #62
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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 a NoMethodError for NilClass somewhere down the
line. 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.
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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. |
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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. |
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Issues
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- Added 3
Complexity increasing per file
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- lib/dry/auto_inject/strategies/constructor.rb 2
Clones added
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- spec/dry/auto_inject_spec.rb 3
See the complete overview on Codacy |
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| # @api private | ||
| def included(klass) | ||
| fail Error, "cannot inject dependencies into a module" unless klass.respond_to?(:new) |
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| context 'autoinject in a module' do | ||
| it 'raises exception' do | ||
| expect { |
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{...} for multi-line blocks.
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| # @api private | ||
| def included(klass) | ||
| fail Error, "cannot inject dependencies into a module" unless klass.respond_to?(:new) |
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3 participants
To me it happened that I accidentally injected my dependencies into a namespace module instead of into a class, like this:
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
#initializemethod 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.