问题
There are several examples for writing a custom ViewHelper and different ways to do things. I have seen examples with render() and with renderStatic (for example in Developing a Custom ViewHelper).
In 24 Fluid Tips there is an explanation, but I don't understand it and it does not make it clear for me why there are 2 functions and what should be used where.
Breaking changes (Render method arguments on ViewHelpers deprecated) and fragmented information in various places makes it difficult to get a clear answer here. Is the example in Developing a Custom ViewHelper up to date and best practice?
回答1:
▸ renderStatic()
First of all, renderStatic() is a static PHP method. This means, you do not have access to instance attributes, such as $this->tag, which is for example required when your ViewHelper class is a subclass of AbstractTagBasedViewHelper.
Another drawback of renderStatic() is that you can not access child nodes. A child node is for example <f:then> in the following example:
<f:if condition="{variable}">
<f:then>
...
</f:then>
</f:if>
Having said that, renderStatic() features the best performance, because it is called from within compiled Fluid. Therefore, this method should be used if possible.
▸ render()
Under certain circumstances, this method is the better choice or has to be used for a specific use case (see explanations above). The logic implemented in a render() method is not compiled, which has an impact on output that is cached.
The downside of render() is its performance.
▸ Summary / Additional Notes
- Use
renderStatic(), if you can (performance). - Use
render(), if you implement an TagBased-ViewHelper (subclass ofTYPO3Fluid\Fluid\Core\ViewHelper\AbstractTagBasedViewHelper). - Use
render(), if you need to read child nodes. - Review the ViewHelpers that are shipped with Fluid (e.g. TYPO3 v9 LTS) as examples.
(see:typo3/sysext/fluid/Classes/ViewHelpers/*) [GitHub]
来源：https://stackoverflow.com/questions/54531152/what-is-the-difference-between-render-and-renderstatic-and-what-should-be-us