gobook

Shadowing

Shadow variable x

func block() {
x := 10
if x > 5 {
	fmt.Println("Inner block", x)
	x:= 5 
	fmt.Println("Reinit inner block:", x)
	}
	fmt.Println("Outer block", x)
}

block()

Inner block 10
Reinit inner block: 5
Outer block 10

Universe block

Redeclaring a variable in the universe block isn't detected by any linters or the shadow tool, be careful not to shadow anything in the universe block.

fmt.Println(true)
true := 10
fmt.Println(true)

true
10

Initializer in if/else statement scope

if n := rand.Intn(10); n == 0 {
	fmt.Println("That's too low")
} else if n > 5 {
	fmt.Println("That's too big:", n)
} else {
	fmt.Println("That's a good number:", n)
}

That's a good number: 1

Notes

Scope

• Outside any function = package block
• Imports = file block
• Inside function / parameters = block
• Anything inside {} is a another block

Access

• Can access any outer scope identifiers