Golang中的无效内存地址

Question

I have checked several other answers and they gave me some good thoughts on how to troubleshoot this but I still can't figure it out.

    localID := generateGenericID("local") // type int64
    localName := "local" // type string

    // set them to pointers as I need them as type *int64 and *string
    plocalID := &localID
    plocalName := &localName

    // create a pointer to a new github org
    var org *github.Organization

    // create a new general purpose org
    o := Org{}

    // Check for nil, per several other answers
    if plocalName != nil {
        o.Name = plocalName
        org.Login = plocalName // ERROR
    }

    if plocalID != nil {
        o.ID = plocalID
        org.ID = plocalID
    }

   fmt.Println(*plocalName) // prints local


    hunt.addOrganization(org) // takes a pointer to a github org
    report.addReportOrganization(&o) // take a pointer to an org

The error message I am getting is:

panic: runtime error: invalid memory address or nil pointer 

It points to the line marked ERROR. The error makes no sense due to me checking for nil, so I am wondering if maybe I am some kind of pointer hell due to creating a variable that is a pointer and then assigning pointers to it.

Should I simply create the github org as a normal struct and then pass in &org to the hunt function. I tried that and got past the error but a ton of other code pukes so before I start to chase this down I figured I would ask if that even makes sense of if I am looking in the wrong spot. RTFM with links is always welcome.

Thanks!

Answer 1

Your code does essentially this:

var org *github.Organization
org.Login = plocalName

org is a nil pointer, it doesn't point to a value, so org.Login tries to de-reference a nil pointer - hence the error. So don't declare org as a pointer type.

You also have a lot of unnecessary code dealing with pointers, e.g.

plocalID := &localID
..
if plocalID != nil {
    o.ID = plocalID
    org.ID = plocalID
}

On that first line you created plocalID and initialized it with &localID. There is no way plocalID can then be a nil pointer, so it doesn't make sense to have the if plocalID != nil { check. You can just get rid of the plocalID and write your code as

o.ID = &localID
org.ID = &localID