Question

下面是一个结构Config，它包含一个返回ReturnNewAddress接口的匿名函数net.Conn。然后使用ReturnNewAddress返回'addr'。

type struct Config { 

    ReturnNewAddress func(net.Conn, error) 

}

稍后在下面调用匿名函数ReturnnewAddress时，请注意cfg是Config的实例。

addr, err := cfg.ReturnNewAddress()

所以我的问题是 - 接口net.Conn如何知道使用什么功能，因为接口具有许多不同的功能？让我感到困惑的是LocalAddr()或RemoteAddr()没有被隐含地调用。如何明确使用这些方法之一。如果我需要LocalAddr明确使用RemoteAddr，该怎么办？

以下是net.Conn的go doc：

type Conn interface {
    // Read reads data from the connection.
    // Read can be made to time out and return an Error with Timeout() == true
    // after a fixed time limit; see SetDeadline and SetReadDeadline.
    Read(b []byte) (n int, err error)

    // Write writes data to the connection.
    // Write can be made to time out and return an Error with Timeout() == true
    // after a fixed time limit; see SetDeadline and SetWriteDeadline.
    Write(b []byte) (n int, err error)

    // Close closes the connection.
    // Any blocked Read or Write operations will be unblocked and return errors.
    Close() error

    // LocalAddr returns the local network address.
    LocalAddr() Addr

    // RemoteAddr returns the remote network address.
    RemoteAddr() Addr

    // SetDeadline sets the read and write deadlines associated
    // with the connection. It is equivalent to calling both
    // SetReadDeadline and SetWriteDeadline.
    //
    // A deadline is an absolute time after which I/O operations
    // fail with a timeout (see type Error) instead of
    // blocking. The deadline applies to all future and pending
    // I/O, not just the immediately following call to Read or
    // Write. After a deadline has been exceeded, the connection
    // can be refreshed by setting a deadline in the future.
    //
    // An idle timeout can be implemented by repeatedly extending
    // the deadline after successful Read or Write calls.
    //
    // A zero value for t means I/O operations will not time out.
    SetDeadline(t time.Time) error

    // SetReadDeadline sets the deadline for future Read calls
    // and any currently-blocked Read call.
    // A zero value for t means Read will not time out.
    SetReadDeadline(t time.Time) error

    // SetWriteDeadline sets the deadline for future Write calls
    // and any currently-blocked Write call.
    // Even if write times out, it may return n > 0, indicating that
    // some of the data was successfully written.
    // A zero value for t means Write will not time out.
    SetWriteDeadline(t time.Time) error
}
    Conn is a generic stream-oriented network connection.

Answer 1

问题不完全清楚，但是......

看起来Config类型的代码有一个拼写错误

   ReturnNewAddress func(net.Conn, error)

没有与后面的代码兼容的函数类型

addr, err := cfg.ReturnNewAddress()

我认为配置结构类型应该定义为

type struct Config { 
    ReturnNewAddress func()(net.Conn, error) 
}

基于此，从addr调用返回的变量cfg.ReturnNewAddress()具有类型net.Conn - 因此它是实现接口net.Conn的值。因此，您可以按如下方式显式调用所需的函数：

localAddr  :=addr.LocalAddr();
remoteAddr := addr.RemoteAddr();

如果一个接口的调用不是隐式的，那么对接口的调用如何访问它？

1 个答案: