Go:
Interpolating a string

How to:

In Go, string interpolation is commonly achieved using the fmt package, particularly with the Sprintf function, which lets you inject variables into a string by specifying formatting verbs. The verbs are placeholders in the format string and are replaced by the given variables’ values. Here’s how you use it:

package main

import (
    "fmt"
)

func main() {
    name := "Jane"
    age := 28

    // Using Sprintf for string interpolation
    message := fmt.Sprintf("Hello, my name is %s and I am %d years old.", name, age)
    fmt.Println(message) // Output: Hello, my name is Jane and I am 28 years old.
}

Note that %s is used for strings, and %d for integers. The fmt package documentation provides a comprehensive list of formatting verbs for different data types.

Deep Dive

The concept of string interpolation exists in many programming languages, albeit with different syntaxes and capabilities. In Go, while the fmt package’s Sprintf function is the most commonly used approach, it might not always be the most efficient, especially for simple concatenations or when working within highly performance-sensitive code.

The fmt package uses reflection to dynamically interpret the types of the variables at runtime, which, while flexible, incurs overhead. For scenarios where performance is critical, direct string concatenation or the strings.Builder type may offer better alternatives. Direct concatenation is straightforward but can become unwieldy with multiple variables. strings.Builder, on the other hand, provides a more performant and readable way to build complex strings in a loop or when dealing with many variables:

var sb strings.Builder
sb.WriteString("Hello, my name is ")
sb.WriteString(name)
sb.WriteString(" and I am ")
sb.WriteString(strconv.Itoa(age))
sb.WriteString(" years old.")
message := sb.String()

fmt.Println(message) // Outputs the same as before

Ultimately, the choice between fmt.Sprintf, direct concatenation, and strings.Builder depends on the specific requirements of your application, such as the complexity of the string being constructed and performance considerations.