Learn Go Basics

This is based on Udemy Course Go - The Complete Guide, lecture by Maximilian Schwarzmüller.

Pointers

variables that store value's address instead of the actual value.

e.g.

age := 30

in computer memory: value -> 32, address -> 0xc00138475

agePointer := &age -> address -> 0xc00138475

Why do we need this?

• avoid unnecessary value copies
  • when you pass a variable to a function as parameter, go creates a copy of the variable. Later garbage collector comes and cleans. If values are too big/complicated, might be burden. But when you pass value as pointer, this won't happen
• directly mutate values
  • pass pointer to the function instead of variable. same reason as above.
  • function can EDIT the value directly, no return value needed. -> Less Code! (=Less understandable code, unexpected result)

Structs

Group data together and also methods and functions defined by "type"

type Note struct {

}

Interfaces

Also use "type"

type saver interface {

}

Concurrency

Goroutines

use go keyword!

Remember that running a function as goroutine is to run it in a non-blocking way.

go greet("nice to meet you!")

fmt.Println() in greet function will not be printed. go does not return a value, it just dispatches goroutine and doesn't wait for it to complete.

so the program ends before the goroutine finishes.

Channels

To resolve this problem, we use channel. Channel transmit data, it's a communication device.

func slowGreet(phrase string, doneChan chan bool) {
    time.Sleep(3*time.Second)
    fmt.Println(phrase)
    doneChan <- true // sends data to channel
}

func main () {
    done := make(chan bool)
    go slowGreet("nice to meet you!", done)
    <- done // arrow describes the direction of data flow. This end the program after some data came out of the channel.
    // also can do this
    // fmt.Println(<- done)
}

This way the program will end after the execution of slowGreet is completed.