Go supports nested struct inside function but no nested function except lambda, does it mean there is no way to define a nested class inside function?
func f() {
// nested struct Cls inside f
type Cls struct {
...
}
// try bounding foo to Cls but fail
func (c *Cls) foo() {
...
}
}
Thus it feels a bit strange that class is weaken inside function.
Any hints?
Actually it doesn't matter if you want to declare the function with or without a receiver: nesting functions in Go are not allowed.
Although you can use Function literals to achieve something like this:
func f() {
foo := func(s string) {
fmt.Println(s)
}
foo("Hello World!")
}
Here we created a variable foo which has a function type and it is declared inside another function f. Calling the "outer" function f outputs: "Hello World!" as expected.
Try it on Go Playground.
struct?
struct type like the receiver, but it will not be a part of the struct's method set. A Function literal is not a function, it is just a value (which has a function type).
I upvoted icza's answer but just to extend it a little, here's his example slightly modified, showing that variables defined in the outer function are visible to the inner function:
func f(s string) {
foo := func() {
fmt.Println(s)
}
foo()
}
func main() {
f("Hello, World!\n")
}
structis a struct type. Go doesn't have classes.classabove meansstructwith bounding function. Forgive my incorrect expression.