code: function(writer) {
          var me = this,
              needsCopy = true;
              
          if (writer === undefined || typeof writer == 'string') {
              writer = {
                  type: writer
              };
              needsCopy = false;
          }
  
          if (!writer.isWriter) {
              if (needsCopy) {
                  writer = Ext.apply({}, writer);
              }
              Ext.applyIf(writer, {
                  model: me.model,
                  type : me.defaultWriterType
              });
  
              writer = Ext.createByAlias('writer.' + writer.type, writer);
          }
  
          me.writer = writer;
  
          return me.writer;
      }
docs: Sets the Proxy's Writer by string, config object or Writer instance
  
  @param {String/Object/Ext.data.writer.Writer} writer The new Writer, which can be either a type string,
  a configuration object or an Ext.data.writer.Writer instance
  @return {Ext.data.writer.Writer} The attached Writer object