closing nil channel

[Martin Hurton]

What's the behaviour of close(c) when c is nil?

- Martin

[Andrew Gerrand]

A panic caused by a nil pointer dereference.

[Martin Hurton]

Did you find out by reading the language specification or by running a
simple program?

[Francisco Souza]

On Sun, Oct 9, 2011 at 8:46 PM, Martin Hurton <hur...@gmail.com> wrote:

Did you find out by reading the language specification or by running a
simple program?

"Developing the language" would be a nice answer. 

--

Francisco Souza

[Andrew Gerrand]

On Monday, October 10, 2011 10:46:54 AM UTC+11, Martin Hurton wrote:

Did you find out by reading the language specification or by running a
simple program?

It was what I expected intuitively, and I wrote a small program to test it:

package main

func main() {

    var c chan int

    close(c)

}

The spec doesn't specify it. It probably should.

Andrew

[Steven Blenkinsop]

I'm not sure. The relevantiest section of the spec is:

A nil channel is never ready for communication.

Close doesn't really fit here, but the point is that, everywhere else, operations on a nil channel don't panic. Keep in mind that there is the implementation difference:

Trying to send/receive from a nil channel causes a run-time panic. 

Your test program is therefore not really reliable in this area, since the other operations on nil channels aren't working properly yet, either. 

[Andrew Gerrand]

On Monday, October 10, 2011 11:03:21 AM UTC+11, Steven Blenkinsop wrote:

On Sun, Oct 9, 2011 at 7:56 PM, Andrew Gerrand <a...@golang.org> wrote:

The spec doesn't specify it. It probably should.

I'm not sure. The relevantiest section of the spec is:

The spec doesn't even specify that a nil pointer dereference should cause a panic (an outstanding issue), so I'm not surprised to find this corner case missing also.

Andrew