# Go Interface Pointer Receiver Method Error Explained

> Fix the 'does not implement interface (method has pointer receiver)' Go compile error by passing a pointer to the struct value instead of a copy

**URL:** https://sentry.io/answers/interface-pointer-receiver/

---

## The Problem

The error:
./prog.go:23:7: cannot use b (type Bar) as type Foo in argument to Fizzy: Bar does not implement Foo (Fizz method has pointer receiver)

```go
package main

import (
	"fmt"
)

type Foo interface {
	Fizz()
}

type Bar struct {}

func (b *Bar) Fizz() {
	fmt.Println("fizz")
}

func Fizzy(foo Foo) {
	foo.Fizz()
}

func main() {
	b := Bar{}
	Fizzy(b)
}
```

## The Solution

This error happens because the pointer to a type is its own unique type. In this example, `*Bar` is a different type to `Bar`. The method receiver `Fizz` is defined on the `*Bar` type, not the `Bar` type. So only `*Bar` satisfies the interface `Foo`.

The fix:

```go
package main

import (
	"fmt"
)

type Foo interface {
	Fizz()
}

type Bar struct {}

func (b *Bar) Fizz() {
	fmt.Println("fizz")
}

func Fizzy(foo Foo) {
	foo.Fizz()
}

func main() {
	b := &Bar{}
	Fizzy(b)
}
```

Change `b` to a pointer to a `Bar`. Since `*Bar` satisfies the interface `Foo`, `b` can now be used as a function argument to `Fizzy`.

### Further Reading

If you're looking to get a deeper understanding of how Go application monitoring works, take a look at the following articles:

- [How slow is slow?](https://blog.sentry.io/how-slow-is-slow/)
- [Sentry's unified Go SDK](https://blog.sentry.io/introducing-sentrys-unified-go-sdk/)
- [Getting started with the Go SDK (docs)](https://docs.sentry.io/platforms/go/)

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*Source: [sentry.io/answers/interface-pointer-receiver/](https://sentry.io/answers/interface-pointer-receiver/)*