dongyi0114 2016-06-25 06:20
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传递给http.HandleFunc的函数如何访问http.ResponseWriter和http.Request?

func main() {
    http.HandleFunc("/", handler)
}

func handler(w http.ResponseWriter, r http.Request) {
    // I never declared, initialized or passed w and r. How does this function get access to them?
}
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  • doushenxu7294 2016-06-25 18:32
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    http.HandleFunc knows its given input parms and that 2nd parm will have its own input parms (w http.ResponseWriter, r http.Request) ... so w and r are setup by http.HandleFunc which after it registers func handler as a callback it then invokes passing in w and r ... so responsibility is given to calling context not inside the callback definition itself

    Its a worth while exercise to write your own such pair of functions where one is a callback passed into and invoked by other function ... this pattern is orthogonal to golang and is a pervasive tool across languages

    本回答被题主选为最佳回答 , 对您是否有帮助呢?
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