为什么可以将参数传递给类似http.Dir（“。”）的类型？

Question

In http package it is defined a custom type (type Dir string) and then a method Open is added to it (https://golang.org/src/net/http/fs.go#L34). When invoked elsewhere it is done by http.Dir(".") as it were a function or method. Can someone explain me why and what is happening here?

Answer 1

http.Dir(".") is a type conversion. It converts the string "." to type http.Dir.