[go-nuts] len() and cap() on channels

The language specification - http://golang.org/ref/spec#Length_and_capacity
- says "The length and capacity of a nil slice, map, or channel are 0.".

However, it seems to work - http://play.golang.org/p/N-BtX758Hn (included
below for ease of read, too):

package main

import "fmt"

func main() {
c := make(chan int, 2)
fmt.Println("cap", cap(c))
fmt.Println("len", len(c))
c <- 1
c <- 2
fmt.Println("len", len(c))
fmt.Println(<-c)
fmt.Println(<-c)
fmt.Println("len", len(c))
}

So, which one here is it? :-)

1) I misunderstand the spec.
2) The spec is wrong.
3) The implementation is doing more than promised and it might go away.
4) Something I didn't think of.

This came up as a "sidebar" on
stackoverflow: http://stackoverflow.com/questions/15858658/do-go-channels-preserve-order-when-blocked


Ask