Channel Selection

It is likely that in an application there are multiple threads each possibly sending and receiving on multiple channels.

The alt Statement

The qualifiers in the alt statement must be expressions containing the channel communication operator, <-.

If there is no channel ready to send or receive, and a default qualifer, *, is present, then the default is selected. If the default qualifier is not present, then the statement blocks until a channel is ready.

Each qualifer and the statements that follow up to the next qualifier form a block. Like case statements, each block breaks by default; no explicit break statement is needed.

Its syntax is similar to the case statement. For example:

	outchan := chan of string;
	inchan := chan of int;
	i := int;
	alt {
		i = <- inchan =>
			...
		outchan <- = "sent" =>
			...
	}