Why Use an Empty `_ struct{}` Field in a Go Struct?

Purpose of an Empty Struct Field with an Underscore Name

Enforcing Keyed Fields in Structs

In Go, there's a coding technique involving an empty struct field named with an underscore ("_"). Understanding its purpose is crucial for developers.

Problem:

SomeType struct contains "_ struct{}" field. What does it achieve?

Answer:

The empty struct field named with an underscore enforces the use of keyed fields when declaring a struct.

For instance, the following struct can only be declared with keyed fields:

type SomeType struct {
Field1 string
Field2 bool
_ struct{}
}

Keyed fields ensure that field names are explicitly specified upon instantiation, enhancing code readability and preventing potential errors.

bar := SomeType{Field1: "hello", Field2: true} // Allowed

foo := SomeType{"hello", true} // Compile error

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