Golang function return value type derivation mechanism

In the Go language, a function return value type derivation mechanism exists. The compiler deduce the return value type according to rules: Multiple return values: Each return value deduce the actual type. The single return value is untyped: the same type as the actual value is deduced. No return value: void type is deduced.

Golang function return value type derivation mechanism

In the Go language, functions can declare multiple return value types, including basic types, structural types, Error types and so on. However, sometimes we do not need to explicitly specify the return value type, but can let the compiler infer the return value type. This process is called type inference.

Rules of type derivation

The compiler deduce the return value type according to the following rules:

• If a function has multiple return values, each return value will A type is derived.
• If a function has only one return value, and the return value does not specify a type, the compiler will infer a type that is the same as the actual return value type in the function call expression.
• If the function has no return value, the compiler will infer a void type.

Practical case

Example 1: Multiple value return

func getPersonDetails() (string, int, bool) {
    return "John Doe", 30, true
}

In this example, the compiler will deduce the following return value type :

• string
• int
• ##bool

Example 2: Single value return

func getFirstName() string {
    return "John"
}

The compiler will deduce the

string type.

Example 3: No return value

func printMessage() {
    fmt.Println("Hello")
}

The compiler will infer the

void type.

Advantages

Type derivation provides the following advantages:

Concise code: Redundant code for specifying the return value type is reduced.
• Readability: Improves the readability of the code, making it easier for developers to understand the semantics of the function.
• Avoid errors: Improve the robustness of your code by eliminating the possibility of specifying the wrong return value type.

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