Question

I just started diving into Go recently and I have one major point of confusion: I am struggling to understand when exactly it is necessary to dereference a pointer explicitly.

For example I know that the . operator will handle dereferencing a pointer

ptr := new(SomeStruct)
ptr.Field = "foo" //Automatically dereferences

In what other scenarios does go do this? It seems to for example, with arrays.

ptr := new([5][5]int)
ptr[0][0] = 1

I have been unable to find this in the spec, the section for pointers is very short and doesn’t even touch dereferencing. Any clarification of the rules for dereferencing go’s pointers would be great!

Answer 1

The selector expression (e.g. x.f) does that:

Selectors automatically dereference pointers to structs. If x is a pointer to a struct,
x.y is shorthand for (*x).y; if the field y is also a pointer to a struct, x.y.z is
shorthand for (*(*x).y).z, and so on. If x contains an anonymous field of type *A, where
A is also a struct type, x.f is a shortcut for (*x.A).f.

The definition of the index expressions specifies that an array pointer may be indexed:

For a of pointer to array type:

• a[x] is shorthand for (*a)[x]