GoLang Tutorial - Structs and receiver methods

A struct is just a collect of fields.

In the following code, we define a struct called "Person", and then initialize it in two ways.

Note that we can not only access a specific field of a struct but also we can modify the value of any field.

Go does not have classes. However, we can define methods on types.

A method is a function with a special receiver argument.

The following example shows how we use (or create) the method of the struct.

In the code, we defined a method called (p Person) hello():

func (p Person) hello() {}

It is a receiver in Go terms and the syntax looks like this:

It's a Go way of creating a method for a struct!

As commented in the code below, it's a value type. We'll soon see a pointer type receiver like this:

func (p *Person) hasBirthday() {}

Here is our full code:

The next example shows how we modified the data of the struct. In the code, we defined a method (receiver) called (p *Person) hasBirthday(). Note that it's taking a pointer:

Another example of a receiver:

The code: stringer.go

We made a method called String() which enables us to customize print for the Animal struct.

Similar to the previous example. This time, we customize the IP-addresses:

The code: ip_addr.go

We made a method called String() which enables us to customize print for the [4]byte array. For instance, IPAddr{1, 2, 3, 4} will be print as "1.2.3.4".

The following is an example code showing one of the ways of constructing a struct.

First, it creates an empty slice of struct pointers, create a struct struct pointer, filled in the elements of the struct, then finally attach the struct pointer to the list of pointers:

The code: city-struct.go

Go Tutorial

1. GoLang Tutorial - HelloWorld
2. Calling code in an external package & go.mod / go.sum files
3. Workspaces
4. Workspaces II
5. Visual Studio Code
6. Data Types and Variables
7. byte and rune
8. Packages
9. Functions
10. Arrays and Slices
11. A function taking and returning a slice
12. Conditionals
13. Loops
14. Maps
15. Range
16. Pointers
17. Closures and Anonymous Functions
18. Structs and receiver methods
19. Value or Pointer Receivers
20. Interfaces
21. Web Application Part 0 (Introduction)
22. Web Application Part 1 (Basic)
23. Web Application Part 2 (Using net/http)
24. Web Application Part 3 (Adding "edit" capability)
25. Web Application Part 4 (Handling non-existent pages and saving pages)
26. Web Application Part 5 (Error handling and template caching)
27. Web Application Part 6 (Validating the title with a regular expression)
28. Web Application Part 7 (Function Literals and Closures)
29. Building Docker image and deploying Go application to a Kubernetes cluster (minikube)
30. Serverless Framework (Serverless Application Model-SAM)
31. Serverless Web API with AWS Lambda
32. Arrays vs Slices with an array left rotation sample
33. Variadic Functions
34. Goroutines
35. Channels ("<-")
36. Channels ("<-") with Select
37. Channels ("<-") with worker pools
38. Defer
39. GoLang Panic and Recover
40. String Formatting
41. JSON
42. SQLite
43. Modules 0: Using External Go Modules from GitHub
44. Modules 1 (Creating a new module)
45. Modules 2 (Adding Dependencies)
46. AWS SDK for Go (S3 listing)
47. Linked List
48. Binary Search Tree (BST) Part 1 (Tree/Node structs with insert and print functions)
49. Go Application Authentication I (BasicAuth, Bearer-Token-Based Authentication)
50. Go Application Authentication II (JWT Authentication)