Channel States and Operations

A channel value is always in one of three states. A nil channel is a channel variable that holds no channel, because make was never called for it. An open channel is a channel created by make that has not been closed. A closed channel is a channel on which close has been called.

A channel created by make starts open and becomes closed when close is called on it. There is no operation that reopens a closed channel. Assigning nil to a variable does not close or otherwise change the channel it held before; the variable simply no longer refers to that channel.