通道作为参数，为什么不加星号？

Question

When I pass a channel as a parameter to close it at the end of the function, I don't need to put * before it to refer to the channel in the main-function scope. But when I'm supposed to set a WaitGroup to done (wg.Done()) I have to so, why is that?

Answer 1

That's because internally, the chan is somewhat a struct made of pointers. You don't need to send a pointer to it. On contrary, the sync.WaitGroup is a classical struct

type WaitGroup struct {
    state1 [12]byte
    sema   uint32
}

for whose all methods are declared with a pointer receiver, so you need to pass a pointer to it around to use it in different scopes.