defining preprocessors for extjs4

gistfile1.js

//add set default xtype preprocessor
Ext.Class.registerPreprocessor('default_xtype', function(cls, data) {
    var className = data.$className;
    var re = new RegExp(/^cl.view./);
    if (re.test(className) && !data.alias) {
        data.alias = 'widget.' + className.replace(re, '').replace(/\./g, '_').toLowerCase();
        /* 
         * Overide default initComponent for defining component config by cloning
         * this section from component class body (componentConfig property).
         * WARNING: you can define component configuration in class body but this configuration
         * will be store in prototype class and each instance of this class 
         * manipulate of this data from prototype. This behavior generate many
         * bugs with recreating components and etc. So use componentConfig.
         *
         */
        var initComponentFn = data.initComponent;
        data.initComponent = function() {
            var me = this,
                config = Ext.clone(me.componentConfig);
            if(config) {
                Ext.apply(me, Ext.apply(me.initialConfig, config));
            }
            if(initComponentFn) {
                initComponentFn.apply(me, arguments);
            } else {
                me.callParent(arguments);
            }
        };
    }
}, true);
Ext.Class.defaultPreprocessors.push('default_xtype');