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POEvent/Class Design Pattern (Prototype)
 

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    <p>I've bumped up against this before and I need the help of someone smarter than me! </p> <p>How can I attach an event of an element to a method of a class? More specifically, the same class? Is there a better way?</p> <p>Using a Qt widget style approach, I've been trying to create self-contained "widget" objects in javascript. I'm using the Prototype javascript framework and building my widget as a class. Then, using Event.observe, I've tried to attach the event to a method of the class. But the Event assignment unbinds the assigned method. Here's an example of a simple table I'm trying to build that has clickable column headers:</p> <pre><code> Objectify.Grid.Table = Class.create({ initialize: function(headers) { this.columns = headers; this.rows = []; }, addRow: function(GridData) { var len = this.rows.push(GridData); return len-1; }, getRow: function(rowIndex) { return this.rows[rowIndex]; }, build: function(parent) { this.mainTable = new Element('table',{'class':'Objectify-Grid'}); $(parent).update(this.mainTable); var tableBody = new Element('tbody',{}); this.mainTable.update(tableBody); var headerRow = new Element('tr',{'class':'Objectify-Grid-header-row'}); tableBody.update(headerRow); this.columns.each(function(val,id) { var hcell = new Element('td',{'class':'Objectify-Grid-header-cell'}).update(val); headerRow.insert(hcell); // EVENT ASSIGNMENT // hcell.observe('click',this.respondToClick); ///////////////////// }.bind(this)); this.rows.each(function(GridData,id) { var row = new Element('tr',{'class':'Objectify-Grid-row','id':'Objectify-Grid-row'+id}); tableBody.insert(row); this.columns.each(function(columnName,index) { var cell = new Element('td',{'class':'Objectify-Grid-cell'}).update(GridData.getValue(columnName)); row.insert(cell); }); }.bind(this)); }, // RECEIVING METHOD // respondToClick: function(event) { var columnName = event.element().innerHTML; // "this" is no longer bound in this method this.sortColumnAsc(columnName); // [ERROR] } }); </code></pre>
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