什么是“<<”的目的? (小于2)在常规 [英] What is the purpose of "<<" (double less than) in groovy
问题描述
我在一些代码中看到了我无法理解<<<<如下面的示例代码所示:
def renderFiles(args){
def model = []
args .each {fileArgs - >
模型<< createModel(fileArgs.id,fileArgs.path,fileArgs.ext)
}
render view:'show',model:[files:model]
}
解决方案这是一个
leftShift
运算符。在groovy中,运算符重载已实现,请参阅此处和 新文档 以供参考。在这种特殊情况下,将一个元素添加到列表操作中会被重载。
不是:
model.add(createModel(fileArgs.id,fileArgs您可以简单地写:
model<< createModel(fileArgs.id,fileArgs.path,fileArgs.ext)
这是一种简写。 List类还有其他的操作符被重写,例如
plus()
,minus()
。请参阅此处。I saw in some of the code which I am unable to understand the purpose of << like in the following sample code
def renderFiles(args) { def model = [] args.each { fileArgs -> model << createModel(fileArgs.id,fileArgs.path,fileArgs.ext) } render view:'show', model: [files:model] }
解决方案This is a
leftShift
operator. In groovy operator overloading is implemented, see here and the new docs for reference . In this particular case adding an element to list operation is overloaded.Instead of:
model.add(createModel(fileArgs.id,fileArgs.path,fileArgs.ext))
You can simply write:
model << createModel(fileArgs.id,fileArgs.path,fileArgs.ext)
It's a kind of a shorthand. There are also other operators overridden for List class, e.g.
plus()
,minus()
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