Go Memory Allocation: When Should I Use `new()` vs. `&`?

Beyond Allocation: Exploring the Distinctions Between new() and Regular Allocation

In Go, memory management is of utmost importance, and allocating memory through the new() function or the ampersand (&) has fueled debates regarding efficiency and precision. This article will delve into the nuances of these two allocation methods, examining their similarities and potential differences.

new() vs. Regular Allocation: A Closer Look

At first glance, the code snippets you provided may seem indistinguishable:

v := &Vector{}

versus

v := new(Vector)

However, closer inspection reveals that they share a commonality: the returned value in both cases is a pointer to a new instance of the Vector struct. This is evident from the following code example:

package main

import "fmt"
import "reflect"

type Vector struct {
    x   int
    y   int
}

func main() {
    v := &Vector{}
    x := new(Vector)
    fmt.Println(reflect.TypeOf(v))
    fmt.Println(reflect.TypeOf(x))
}

Output:

*main.Vector
*main.Vector

As shown, both methods return pointers to instances of the Vector struct.

The Confusion Conundrum

The existence of both new() and regular allocation has sparked confusion within the Go community. Some argue that having both options is unnecessary, potentially leading to misunderstandings. This debate was prevalent on the Go mailing list:

[https://groups.google.com/forum/?fromgroups=#!topic/golang-nuts/GDXFDJgKKSs](https://groups.google.com/forum/?fromgroups=#!topic/golang-nuts/GDXFDJgKKSs)

Notable Differences: An Exception

While the general consensus is that new() and regular allocation yield similar results, there is one notable exception. When working with unnamed integer types or other basic types, new() becomes the only option for obtaining a pointer. The following code demonstrates this:

p := new(int)
// Error: cannot take the address of the type int
p := &int{0}

In this scenario, new() is the only method that allows for the creation of a pointer to an unnamed integer type.

Conclusion

While there is no significant difference between new() and regular allocation in terms of the returned value, their presence can introduce confusion. However, remembering that new() is essential when dealing with pointers to unnamed integer or basic types can help clarify their usage and avoid potential pitfalls. By understanding the subtleties of memory management techniques in Go, developers can optimize their code for efficiency and clarity.

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