lib/Ext/direct/Manager.js
function(fn) {
        if (Ext.isString(fn)) {
            var parts = fn.split('.'),
                i = 0,
                ln = parts.length,
                current = window;

            while (current && i < ln) {
                current = current[parts[i]];
                ++i;
            }
            fn = Ext.isFunction(current) ? current : null;
        }
        return fn || null;
    }
function(fn) {
        if (Ext.isString(fn)) {
            var parts = fn.split('.'),
                i = 0,
                ln = parts.length,
                current = window;

            while (current && i < ln) {
                current = current[parts[i]];
                ++i;
            }
            fn = Ext.isFunction(current) ? current : null;
        }
        return fn || null;
    }
Parses a direct function. It may be passed in a string format, for example:
"MyApp.Person.read".
@protected
@param {String/Function} fn The direct function
@return {Function} The function to use in the direct call. Null if not found