3. Viewed 4k times 9. The Print() methods accept a receiver pointer. Pointers and interfaces. There are two reasons to use a pointer receiver. Hence, the interface must also accept a receiver pointer. Another subtlety of interfaces is that an interface definition does not prescribe whether an implementor should implement the interface using a pointer receiver or a value receiver. When you are given an interface value, there’s no guarantee whether the underlying type is or isn’t a pointer. It is also possible to implement interfaces using pointer receivers. It is to be noted that the pointer receiver can also be used to implement an interface. Custom errors in golang and pointer receivers. Choosing a value or pointer receiver. This can be more efficient if the receiver is a large struct, for example. A method of a type can either have a pointer receiver or a value receiver. In this tutorial we will learn how pointers work in Go and we will also understand how Go pointers differ from pointers in other languages such as C and C++. Ask Question Asked 2 years, 6 months ago. Reading about value receivers vs pointer receivers across the web and stackoverflow, I understand the basic rule to be: If you don't plan to modify the receiver, and the receiver is relatively small, there is no need for pointers. While methods with interface (value) receivers are clearly not possible, methods with interface pointer receivers (and consequently having interface pointers implement other interfaces) should be possible. In the above examples, we only worked with the value receiver. Active 1 year, 7 months ago. The recursion continues, with calling the method on a NIL pointer receiver. The first is so that the method can modify the value that its receiver points to. Part 15: Pointers 13 April 2019. But there is a caveat here Currently, methods are not allowed to have an interface receiver or an interface pointer receiver. Declaring pointers; Zero value of a pointer Pointer Receiver while implementing an interface. The second is to avoid copying the value on each method call. Further investigations shows that all of the following changes would solve the problem: Pointer vs Value Receiver in methods while implementing an interface in Go (Golang) Posted on July 18, 2020 July 18, 2020 by admin. What is a pointer? All the example interfaces we discussed in part 1 were implemented using value receivers. I'm just building a simple list using an interface type as parent attribute. Interface Accepting Address of the Variable. There is a subtlety to be noted while implementing interfaces using pointer receivers. A method of a type can either have a pointer receiver or a value receiver. 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