In this case, the lambda function remains nameless: It is created inline as a parameter to the array_filter function. 在本例中,lambda函数保持没有名字:它是在内侧作为arrayfilter函数的参数来创建的。
As we saw in the examples for lambda functions, one of the most obvious uses for closures is in the few PHP functions that accept a callback function as a parameter. 如在lambda函数的示例中所示,闭包的最明显用法之一是少数PHP函数接受回调函数作为参数。