owl/doc/tooling.md

🦉 Tooling 🦉

Content

• Overview
• Playground
• Benchmarks
• Single File Component
• Debugging Script

Overview

To help work with/improve/learn OWL, there are a few extras tools/settings.

• development mode: enable better error reporting for the developer
• a playground application: a space to experiment and learn Owl.
• a benchmarks application: allow comparison with a few common frameworks

The two applications are available in the tools/ folder, and can be accessed by using a static http server. A simple python server is available in server.py. There is also a npm script to start it: npm run tools (and its version with a watcher: npm run tools:watch).

Playground

The playground is an important application designed to help learning and experimenting with Owl. The last published version of Owl can be tested online.

It is an application similar to jsFiddle, but specialized for Owl: there are three tabs (js, css and xml), and a simple button Run to execute that code in an iframe.

Benchmarks

Note: This is more an internal tool, useful for people working on Owl.

The benchmarks application is a very small application, implemented in different frameworks, and in different versions of Owl. This is a simple internal tool, useful to compare various performance metrics on some tasks.

Single File Component

It is very useful to group code by feature instead of by type of file. It makes it easier to scale application to larger size.

To do so, Owl currently has a small helper that makes it easy to define a template inside a javascript (or typescript) file: the xml helper. With this, a template is automatically registered to QWeb.

This means that the template and the javascript code can be defined in the same file. It is not currently possible to add css to the same file, but Owl may get a css tag helper later.

const { Component } = owl;
const { xml } = owl.tags;

// -----------------------------------------------------------------------------
// TEMPLATE
// -----------------------------------------------------------------------------
const TEMPLATE = xml/* xml */ `
	<div class="main two-columns">
		<Sidebar/>
		<Content />
	</div>`;

// -----------------------------------------------------------------------------
// CODE
// -----------------------------------------------------------------------------
class MyComponent extends Component {
  static template = TEMPLATE;
  static components = { Sidebar, Content };

  // rest of component...
}

Note that the above example has an inline xml comment, just after the xml call. This is useful for some editor plugins, such as the VS Code addon Comment tagged template, which, if installed, add syntax highlighting to the content of the template string.

Debugging Script

Debugging

Non trivial applications become quickly more difficult to understand. It is then useful to have a solid understanding of what is going on. To help with that, logging useful information is extremely valuable. There is a javascript file which can be evaluated in an application.

Once it is executed, it will log a lot of information on each component main hooks. The following code is a minified version to make it easier to copy/paste:

function debugOwl(t,n){let e,o="[OWL_DEBUG]";function s(t){let n=JSON.stringify(t||{});return n.length>200&&(n=n.slice(0,200)+"..."),n}if(Object.defineProperty(t.Component,"current",{get:()=>e,set(i){e=i;const r=i.constructor.name;if(n.componentBlackList&&n.componentBlackList.test(r))return;if(n.componentWhiteList&&!n.componentWhiteList.test(r))return;let l;Object.defineProperty(e,"__owl__",{get:()=>l,set(e){!function(e,i,r){let l=`${i}<id=${r}>`,c=t=>console.log(`${o} ${l} ${t}`),u=t=>(!n.methodBlackList||!n.methodBlackList.includes(t))&&!(n.methodWhiteList&&!n.methodWhiteList.includes(t));u("constructor")&&c(`constructor, props=${s(e.props)}`);u("willStart")&&t.hooks.onWillStart(()=>{c("willStart")});u("mounted")&&t.hooks.onMounted(()=>{c("mounted")});u("willUpdateProps")&&t.hooks.onWillUpdateProps(t=>{c(`willUpdateProps, nextprops=${s(t)}`)});u("willPatch")&&t.hooks.onWillPatch(()=>{c("willPatch")});u("patched")&&t.hooks.onPatched(()=>{c("patched")});u("willUnmount")&&t.hooks.onWillUnmount(()=>{c("willUnmount")});const d=e.__render.bind(e);e.__render=function(...t){c("rendering template"),d(...t)};const h=e.render.bind(e);e.render=function(...t){const n=e.__owl__;let o="render";return n.isMounted||n.currentFiber||(o+=" (warning: component is not mounted, this render has no effect)"),c(o),h(...t)};const p=e.mount.bind(e);e.mount=function(...t){return c("mount"),p(...t)}}(i,r,(l=e).id)}})}}),n.logScheduler){let n=t.Component.scheduler.start,e=t.Component.scheduler.stop;t.Component.scheduler.start=function(){this.isRunning||console.log(`${o} scheduler: start running tasks queue`),n.call(this)},t.Component.scheduler.stop=function(){this.isRunning&&console.log(`${o} scheduler: stop running tasks queue`),e.call(this)}}if(n.logStore){let n=t.Store.prototype.dispatch;t.Store.prototype.dispatch=function(t,...e){return console.log(`${o} store: action '${t}' dispatched. Payload: '${s(e)}'`),n.call(this,t,...e)}}}
debugOwl(owl, {
  // componentBlackList: /App/,  // regexp
  // componentWhiteList: /SomeComponent/, // regexp
  // methodBlackList: ["mounted"], // list of method names
  // methodWhiteList: ["willStart"], // list of method names
  logScheduler: false,  // display/mute scheduler logs
  logStore: true,     // display/mute store logs
});

Note that it is certainly useful to run this code at some point in an application, just to get a feel of what each user action implies, for the framework.