It bucks the conventional understanding of how signals might be used, but it means that we don’t need this distinction.
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Our view models are a collection of inputs and outputs. Some of which are effectful. All of which are signals.
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What does it mean for an output to be effectful?
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e.g., resulting in the presentation of a new view controller, or the view model beginning a network request.
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OK. How do you express those effects as outputs in the interface?
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My point is exactly that _you don’t need to_. Why is it important? The effects are an implementation detail.
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Trying to figure out how this is different from any object which performs effects when it e.g. receives a message.
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Is the significant point that all endpoints are expressed via signal APIs rather than via methods?
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Yes. Everything can be treated as a functional series of inputs to outputs. Embedded effects are encapsulated away.
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Here’s one of my favorite examples: github.com/ReactiveCocoa/
I just embedded an animation effect, but it’s the same values.
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Man, the embedding of effects makes me super duper uncomfortable. How do you test this stuff? Mocks?
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Generally, we don’t test any of the effects themselves—they’re usually untestable things. The signals are still testable.
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(For example, we don’t test animation or layout, but we _could_ verify the layout signal without caring that it animates.)
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