Jason’s postings and stuff

It’s always nice to stumble upon patterns that make code both functional and beautiful at the same time. Among those, of late I have been abusing these patterns when developing ExtJS components.

For example, a pattern from ExtJS itself uses Ext.applyIf to both ensure an object literal exists and then to apply default values unless they’re already defined. Such a pattern can find widespread use in any project.

this.simpleConfig = Ext.applyIf(this.simpleConfig||{}, {
  width:500,
  height:250
});

Another I rather enjoy I first noticed in an Ext Direct implementation for Rails. The functions being applied are defined after the plugin on a function prototype specifically for that purpose. It’s nice and clean.

liaison.klass.plugin.OnData = Ext.extend(Object, {
	constructor:function(config) {
		Ext.apply(this, config);
	},
 
	init:function(p) {
		Ext.applyIf(p, liaison.klass.plugin.OnData.Methods.prototype);
		p.addEvents('data', 'update-data', 'create-data', 'delete-data');
		p.on('data', p.onData, p);
	}
});
 
liaison.klass.plugin.OnData.Methods = function() {};
liaison.klass.plugin.OnData.Methods.prototype = {
 
	onData:function(action, result) {
		this.fireEvent(action+"-data", this[action+"Record"](result));
	}
};

Another pattern from ExtJS itself I hadn’t thought to mention, above, is concisely defining and calling functions based on some string. For example, I avoid the need for a case statement or an if block when deciding amongst functions prefixed with the string action. Instead, onData is a compound one liner that fires an event based on the results of a conditionally named function. Fun!

Finally, I noticed a short pattern for managing namespaces in a plugin by ExtJS forum member stephen.friedrich. I employ it when building up my various FormPanel classes.

(function() {
  var ns = Ext.ns('liaison.view.form.membership');
  ns.NewPanel = Ext.extend(liaison.components.form.DefaultFormPanel, {
  ...
  });
  Ext.reg('membership-new-form', ns.NewPanel);
)();

Simple, but effective. It’s nice to collect private field configuration items in local variables.

What patterns do you enjoy using?