2016-11-09 11:02:57 +00:00
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# 2. Contain and manage state
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Date: 09/11/2016
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## Status
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Accepted
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## Context
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2016-11-17 21:53:21 +00:00
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The hardest part of debugging Page Previews issues (especially those related to
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2016-11-09 11:02:57 +00:00
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EventLogging) was understanding the state of the system (the "state") and how
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it's mutated given some interaction(s). This was in no small part because the
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state was defined, initialized, and mutated in various parts of the codebase.
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2016-11-17 21:53:21 +00:00
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The state required for Page Previews to function isn't actually overly
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2016-11-09 11:02:57 +00:00
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complicated. To keep things easy to debug/easy to reason about we should
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endeavour to isolate the state and its mutations from the various other parts of
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the system.
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## Decision
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Use [Redux](http://redux.js.org).
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## Consequences
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* Newcomers will have to familiarise themselves with the library (especially
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it's nomenclature).
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* All changes will have to be broken down into: the additional state that they
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require; actions that are dispatched; and how the state is mutated as a result
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of those actions. This requires discipline.
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* We benefit from using a tool that is part of an increasingly rich ecosystem,
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e.g. see [Redux DevTools Extension](https://github.com/zalmoxisus/redux-devtools-extension).
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