re-frame-trace

A trace window for re-frame

Motivation

re-frame provides a data driven architecture, but we need to be able to inspect it. re-frame-trace takes inspiration from redux-devtools, and provides several ways to visualise the structure and state of your re-frame application.

How does it work?

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].

Getting started

Compile your app with :closure-defines: "re_frame.trace.trace_enabled_QMARK_" true and :preloads [day8.re-frame.trace.preload], e.g.

    {:builds
       [{:id           "dev"
         :source-paths ["src" "dev"]
         :compiler     {...
                        :closure-defines      {"re_frame.trace.trace_enabled_QMARK_" true}
                        :preloads             [day8.re-frame.trace.preload]}}]}

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.

The 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. The preload namespace also injects a div containing the devtools panel into the DOM.

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.