结构字段还原[重复]

I'm playing with Go a bit but found this weird situation while doing some tests.

I'm using method in a struct to send a variable to another method that should change a field, but when I check it at the end, the field goes back to the first value, which has me confused.

func (this TVManager) sendMessage(message string) {
    fmt.Println("5", this.connector)
    payload := map[string]string {
       "id": "0",
       "type": "request",
       "uri": "ssap://system.notifications/createToast",
       "payload": "{'message': 'This is a message'}"}
    this.connector.sendCommand(payload)
    fmt.Println("4", this.connector)
}

This is the method I'm testing, it calls sendCommand of connector.

func (this MockConnector) sendCommand(payload map[string]string) {
    fmt.Println("0", this)
    this.last_command = payload
    this.value = true
    fmt.Println("0", this)
}

Which in the mock object I'm using is simply changing the value of this struct fields.

    manager.sendMessage("This is a message")

fmt.Println("1", connector)
assert.Equal(t, expected, connector.last_command, "Command should be equal")

But when I check it, it goes back to internal. I set some prints to try an d track the values and they change the values as expected, but then it reverts.

 1 {false map[]}
 5 {false map[]}
 0 {false map[]}
 0 {true map[uri:ssap://system.notifications/createToast payload:{'message': 'This is a message'} id:0 type:request]}
 4 {false map[]}
 1 {false map[]}
 --- FAIL: TestTVManagerSendsNotificationDownToConnector (0.00s)

This is just a small program I'm going over to learn some Go, so I appreciate any help anybody could give me.

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You are passing the structures by value. This works fine so long as you are not modifying the structure, but if you do modify it you are actually only modifying a copy. To make this work you need to use pointers to the structures you need to modify.

Instead of:

func (this MockConnector) sendCommand(payload map[string]string)

Use:

func (this *MockConnector) sendCommand(payload map[string]string)

Also, it is considered a bad idea to use this (or self) as a receiver name in Go, as a receiver is not the same thing as a this pointer/reference in other languages.

Another best practice, is if one method for a given type needs a pointer receiver, all methods for that type should have pointer receivers. This is so that the method set remains consistent no matter if the value is a pointer or not.

See method sets, and these FAQ answers for more information.