I have the function below which accepts a bool pointer. I'm wondering if there is any notation which allows me to set the value of the is
field to true
in the struct literal; basically without to define a new identifier (i.e. var x := true ; handler{is: &x} )
package main
import "fmt"
func main() {
fmt.Println("Hello, playground")
check(handler{is: new(bool) })
}
type handler struct{
is *bool
}
func check(is handler){}
You can do that but it's not optimal:
h := handler{is: &[]bool{true}[0]}
fmt.Println(*h.is) // Prints true
Basically it creates a slice with one bool
of value true
, indexes its first element and takes its address. No new variable is created, but there is a lot of boilerplate (and backing array will remain in memory until the address to its first element exists).
A better solution would be to write a helper function:
func newTrue() *bool {
b := true
return &b
}
And using it:
h := handler{is: newTrue()}
fmt.Println(*h.is) // Prints true
You can also do it with a one-liner anonymous function:
h := handler{is: func() *bool { b := true; return &b }()}
fmt.Println(*h.is) // Prints true
Or a variant:
h := handler{is: func(b bool) *bool { return &b }(true)}
To see all your options, check out my other answer: How do I do a literal *int64 in Go?