How is default value passing implemented in function parameters in Go?

The Go language does not have built-in support for default parameter values in functions, as in some other languages (e.g., Python or C++). To implement similar behavior, the following approaches are usually used:

1. Function overloading via variadic parameters — pass a variable number of arguments to the function and check their presence inside:

func greet(name string, messages ...string) {
    msg := "Hello"
    if len(messages) > 0 {
        msg = messages[0]
    }
    fmt.Println(msg, name)
}

// Calls:
greet("Alice")           // Hello Alice
greet("Bob", "Hi")     // Hi Bob

2. Using configuration structures — pass a struct with parameters to the function, where default values can be set upon creation:

type Config struct {
    Timeout int
}

func doSomething(cfg Config) {
    if cfg.Timeout == 0 {
        cfg.Timeout = 30 // default value
    }
    // ...
}

// Call:
doSomething(Config{})

3. Creating helper constructor functions with different sets of parameters.

Thus, in Go, default values are implemented through explicit logic inside the function or through structures, not through language syntax.