How to use Golang's parameter hiding feature

When using Golang to pass function parameters, we sometimes need some parameters that can only be accessed internally and cannot be called externally. At this time, we can use Golang's parameter hiding function.

Parameter hiding refers to defining the parameter type of a function as a private type so that it can only be used inside the function and is not visible outside the function. This can make the code more elegant and easier to maintain while ensuring the security and encapsulation of the code.

Next, let’s look at some specific examples to illustrate how to use Golang’s parameter hiding function.

First, we define a new type called "age". The underlying type of this new type is an unsigned integer, but because this type is private, external functions cannot access this type.

type age uint8

Next, we define a new function "say" whose parameter type is "age". Since "age" is a private type, the parameters of this function are also private and can only be accessed inside the function.

func say(a age) {
    fmt.Printf("I am %d years old.\n", a)
}

We can use this parameter inside the function, for example:

func main() {
    a := age(18)
    say(a)
}

The above code can run correctly, but if we try to use the "age" type as a parameter outside the function, for example:

func test(a age) {
    fmt.Println(a)
}

func main() {
    a := age(18)
    test(a)
}

will report an error "undefined: age".

Through the above examples, we can see that using Golang's parameter hiding function can make our code safer and more beautiful. At the same time, it can effectively protect private data from direct access by other functions, thus improving the encapsulation and security of the code.

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