io.Reader equivalent of ioutil.Discard

[robn...@gmail.com]

ioutil.Discard provides a writer that goes nowhere. The ioutil source code includes a reader-version specifically for io.Copy, but doesn't make it public. Is there a standard way to handle this? As an example, I'd like to pass an empty reader to a function that closes the reader (so passing nil would crash). I'm currently using a string reader:

    req, err := http.NewRequest("GET", "...", strings.NewReader(""))

I would expect something like `ioutil.DevNull` instead.

-Rob

[James Bardin]

If you're certain only Close() will ever be called, you can pass `ioutil.NopCloser(nil)` (Read will still panic, maybe that's what you want.)

Otherwise, a simple devNull with Read is only a few lines to stub out the methods.

[voidlogic]

Maybe you want: foo := ioutil.NopCloser(bytes.NewReader(nil))

[Brad Fitzpatrick]

You can pass nil to http.NewRequest, btw.

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[Rob Napier]

I was confused about my responsibility to close the request body. I see that I don't actually need to do that, so there's no need to worry about it being nil (I was crashing when I added a "defer request.Body.Close(), but that's not needed).

Thanks,

-Rob

[Rob Napier]

Note that this does panic if you pass nil to a POST request. I know this is an unusual situation, but I'm writing test cases and am testing the case where a POST is sent with no content. The HTTP spec allows POST without a body (there was a somewhat interesting discussion on the IETF forum about that), so if nil is ok to pass to NewRequest(), it seems it should be legal even for POST.

-Rob

--
Rob Napier -- Software and Security Consulting
Cocoaphony blog -- http://robnapier.net/blog

iOS Programming Pushing the Limits -- http://robnapier.net/book

[Brad Fitzpatrick]

Where do you see a panic with a nil Body?  I can't reproduce that.

Please file a bug if so, with example code?