如何生成观察块 [英] How to generate observe block

问题描述

我想像这样生成观察块:

I want to generate the observe block like so:

        created: function () {
            var viewData = {
                type: 'Pikachu',
                name: 'Gary'
            };

            // iterate over view data
            for (prop in viewData) {
                //set the property
                this[prop] = viewData[prop];


                var handlerName = 'update' + prop

                // set add the property to the observe block
                this.observe[prop] = handlerName;

                // set the handler
                this[handlerName] = function (valueWas, valueIs) {
                    console.log('you have changed ' + prop + ' to ' valueIs);
                };
            }
        },

这可能吗?

这对我来说完全没有反应，没有错误，但是没有调用处理程序.

This is being completely unresponsive for me, no errors, but the handler isn't being called.

推荐答案

您缺少一些奥秘.在最终确定原型之前，polymer-element代码将observe映射分解为并行数组，作为(非常烦人的)速度优化.

You are missing some arcana. Before finalizing the prototype the polymer-element code explodes the observe map into parallel arrays as a (highly annoying) speed optimization.

您可以通过以下方式重新优化实例:

You can re-optimize your instance by calling:

this.element.optimizePropertyMaps(this);

this.element指的是定义当前元素类型的polymer-element(首先，众所周知element是此属性的坏名).

Where this.element refers to the polymer-element that defined the current element type (fwiw, it's known that element is a bad name for this property).

这里是一个例子:

http://jsbin.com/tahixumu/4/edit

出于性能考虑，Polymer认为观察者和其他特殊列表是共享原型的功能.由于您的动态数据大概是每个实例的 ，因此，为了进行适当的测试，我不得不使您的示例更加复杂.

Also for performance, Polymer considers the observers and other special lists to be features of a shared prototype. Since your dynamic data is presumably per-instance I had to make your example more complicated for a proper test.

请注意，由于颠覆了Polymer对每个原型的期望，可能还会出现其他并发症.

Keep an eye out, there may be other complications due to subverting Polymer's per-prototype expectations.

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