如何在Go中删除struct对象？

Question

Let's say I have the following struct:

type Person struct {
    name string
    age  int
}

If I make an object of that struct

person1 := Person{name: "Name", age: 69}

If I set this object to nil

person1 = nil

it doesn't work, in fact it's a type assignment error, but it works for maps and slices. So, how otherwise would I remove the object i.e deallocate? I looked at the documentation for delete builtin but it removes an entry from a given map. Thanks.

Answer 1

Go is a garbage collected language. You are not supposed to, and you cannot delete objects from memory. It is the garbage collector's duty and responsibility to do so, and it does this automatically. The garbage collector will properly remove objects from memory when they become unreachable.

You can assign nil to maps and slices because nil is a valid value (the zero value) for those types. The zero value for struct types is not nil but a struct value where all its fields have their zero values.

If you want to clear or overwrite the struct value, you may simply assign another struct value to it, preferably the zero value (an empty struct):

person1 := Person{name: "Name", age: 69}
// work with person1

// Clear person1:
person1 = Person{}

But know that this will not free memory allocated by person1; as wrote earlier, it will be freed automatically by the GC when it becomes unreachable.

nil is also a valid value (the zero value) for pointer types, so if person1 would be a pointer to Person (that is, *Person), you could also assign nil to it, e.g.:

person1 := &Person{name: "Name", age: 69}
// work with person1

// Clear person1:
person1 = nil

When clearing a pointer by setting it to nil, the pointed object –again– will be taken care of by the GC.

For more details about how the garbage collector works, see Golang - Cannot free memory once occupied by bytes.Buffer.