59 lines
2.7 KiB
Markdown
59 lines
2.7 KiB
Markdown
# re-frame-trace
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A trace window for re-frame
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## Motivation
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re-frame provides a data driven architecture, but we need to be able to inspect it. re-frame-trace takes inspiration from [redux-devtools](https://github.com/gaearon/redux-devtools), and provides several ways to visualise the structure and state of your re-frame application.
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<img src="docs/images/trace-window.png" height="400px">
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## How does it work?
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re-frame has instrumentation to collect traces throughout various important points in the lifecycle of a re-frame app. re-frame-trace is a consumer of these traces, and provides visualisations of the traces. These traces have a well-defined structure, and will eventually be standardised, allowing other developers to create their own tooling to work against the traces. Currently, re-frame's tracing and re-frame-trace are in alpha and are subject to change at any time. Caveat usor [sic].
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## Getting started
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There are two requirements to use re-frame-trace:
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1. Compile your app with `:closure-defines: "re_frame.trace.trace_enabled_QMARK_" true` and `:preloads [day8.re-frame.trace.preload]`, e.g.
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```cljs
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{:builds
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[{:id "dev"
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:source-paths ["src" "dev"]
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:compiler {...
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:closure-defines {"re_frame.trace.trace_enabled_QMARK_" true}
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:preloads [day8.re-frame.trace.preload]}}]}
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```
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By default, re-frame tracing is compiled out, so it won't impose a performance cost in production. The trade-off here is that you need to explicitly enable it in development.
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The [preloads](https://github.com/clojure/clojurescript/wiki/Compiler-Options#preloads) option (`:preloads [day8.re-frame.trace.preload]`) has to be set in order to automatically monkeypatch Reagent to add appropriate lifecycle hooks. Yes this is gross, and yes we will try and make a PR to reagent to add proper hooks, once we know exactly what we need.
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2. In your app's view code, add in `day8.re-frame.trace/devtools` as a sibling to the root application view. For example, if your app looks like this:
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```cljs
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(defn main []
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[re-com/v-box
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;; your app here
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])
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(defn ^:export start-app
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[]
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(myapp.boot/init!)
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(reagent/render (fn [] [main]) (.getElementById js/document "app")))
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```
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then you need to modify `main` to look something like:
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```cljs
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(defn main []
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[:div
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[re-com/v-box
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;; your app here
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]
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[trace/devtools]) ;; day8.re-frame.trace is aliased is trace
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```
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Now you can start up your application. Once it is loaded, press Ctrl+H to slide open the trace panel and enable tracing. When the panel is closed, tracing is disabled.
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