I'm new to golang and learning how dereferencing works in nested struct types. When I searched for nested structs normally they would suggest the method suggested by @OneOfOne in How to initialize a nested struct?

However while reading the codebase at work i noticed the team also uses nested pointers. I'm confused when I should use this. ie. nested struct req Person vs a nested pointer req *Person?

example

• Person

  type Person struct {
      Name string
      Age  int8
  }
  

• args

  type args struct {
      req *Person
  }
  

CodePudding user response：

One common use case for pointers in struct attributes (besides struct size) is the optionality of the said attribute. While I do not know about particular use case, I can guess that it might refer to some sort of an optional relationship.

For example: A Customer struct having a LastOrder struct attribute. Since the customer may not even have made a single order yet, it might make sense to keep this as a pointer reference, in order ti signal that it may be nil.

Another use case of using pointer attributes is in graph-like or referential data structures. Think about a Person struct who has both a Mother and a Father attributes. If you set those to be of type Person, the compiler will come back with an error, because the resulting structure will recurse ad-infinitum. In that case, those must be set as pointers too.

Hope the answer helps.

CodePudding user response：

You should use pointers when you want it to be an optional field (because you can simply assign a nil pointer to it when initializing a variable), when a size is big and you want to increase the app's performance, or if you want to have a field that points to a variable of the same type e.g:

type Node struct {
    Data int
    Left *Node
    Right *Node
}