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Stunned by Go

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Re: Stunned by Go

#21

Post by tux21b »

BarkMore wrote: post #6

This issue was recently discussed on the development mail list: https://groups.google.com/d/msg/golang-dev/o9i_SbGRrzI/gWvnB... The fix is to document that Close is called: https://codereview.appspot.com/11432044/

Yes, Roger Peppe, one of the Go contributors, had exactly the same issue, but luckily Brad and Russ, two core devs, were able to solve the mystery immediately and updated the documentation.

It's now quite funny to read a blog post from someone completely different (Tim Penhey) who had encountered and solved the same issue with exactly the same usecase on the very same day, complaining about Go without even mentioning the discussion [1] or the latest changeset [2] that solved the problem.

[1]: https://groups.google.com/d/topic/golang-dev/o9i_SbGRrzI/dis... [2]: https://codereview.appspot.com/11432044

Re: Stunned by Go

#22

Post by thirsteh »

tux21b wrote: post #21
BarkMore wrote: post #6

This issue was recently discussed on the development mail list: https://groups.google.com/d/msg/golang-dev/o9i_SbGRrzI/gWvnB... The fix is to document that Close is called: https://codereview.appspot.com/11432044/

Yes, Roger Peppe, one of the Go contributors, had exactly the same issue, but luckily Brad and Russ, two core devs, were able to solve the mystery immediately and updated the documentation. It's now quite funny to read a blog post from someone completely different (Tim Penhey) who had encountered and solved the same issue with exactly the same usecase on the very same day, complaining about Go without even mentioning…

That is pretty funny, but it doesn't really change anything. It's unfortunate that it called Close() without at least giving proper notice, and most people will probably agree that in a perfect world where we could start over without breaking APIs, the implementation would be different.

Re: Stunned by Go

#23

Post by melvinmt »

usea wrote: post #10
marshray wrote: post #9

> The standard http library was calling Close on my io.Reader. This is not expected behaviour when the interface clearly just takes an io.Reader (which exposes one and only one method Read). So if I implemented my own object with a Reader interface and passed it to this HTTP library, could it find some other method on my object named Close() and it could call it? Is it pure duck typing happening here, or is the HTTP…

In Go, a type doesn't have to declare that it implements an interface; it automatically satisfies an interface if it implements the appropriate methods. Most interfaces in Go only contain one method. If a type has a Close() method, then it is a Closer. The code that tries to cast it to a Closer will succeed. So to answer your question, it doesn't matter what the semantics of your Close() method are, it will succeed s…

> your type has a method with that name.

I would say with the same function signature, not just the name.

Re: Stunned by Go

#24

Post by tux21b »

thirsteh wrote: post #22
tux21b wrote: post #21

Earlier quoted context omitted.

Yes, Roger Peppe, one of the Go contributors, had exactly the same issue, but luckily Brad and Russ, two core devs, were able to solve the mystery immediately and updated the documentation. It's now quite funny to read a blog post from someone completely different (Tim Penhey) who had encountered and solved the same issue with exactly the same usecase on the very same day, complaining about Go without even mentioning…

That is pretty funny, but it doesn't really change anything. It's unfortunate that it called Close() without at least giving proper notice, and most people will probably agree that in a perfect world where we could start over without breaking APIs, the implementation would be different.

I was just criticizing the publishing skills of some people... The problem itself is unfortunate and I am personally not a huge fan of the "no API changes" philosophy participated by the Go team. I can understand the reasons behind it, but it's still hard to read several CLs per day that are abandoned or done differently (in a non-optimal way) because of this contract.

Re: Stunned by Go

#25

Post by jeremyjh »

tux21b wrote: post #21
BarkMore wrote: post #6

This issue was recently discussed on the development mail list: https://groups.google.com/d/msg/golang-dev/o9i_SbGRrzI/gWvnB... The fix is to document that Close is called: https://codereview.appspot.com/11432044/

Yes, Roger Peppe, one of the Go contributors, had exactly the same issue, but luckily Brad and Russ, two core devs, were able to solve the mystery immediately and updated the documentation. It's now quite funny to read a blog post from someone completely different (Tim Penhey) who had encountered and solved the same issue with exactly the same usecase on the very same day, complaining about Go without even mentioning…

Documenting this does not solve the problem.

Re: Stunned by Go

#26

Post by [deleted] »

tux21b wrote: post #21
BarkMore wrote: post #6

This issue was recently discussed on the development mail list: https://groups.google.com/d/msg/golang-dev/o9i_SbGRrzI/gWvnB... The fix is to document that Close is called: https://codereview.appspot.com/11432044/

Yes, Roger Peppe, one of the Go contributors, had exactly the same issue, but luckily Brad and Russ, two core devs, were able to solve the mystery immediately and updated the documentation. It's now quite funny to read a blog post from someone completely different (Tim Penhey) who had encountered and solved the same issue with exactly the same usecase on the very same day, complaining about Go without even mentioning…

[deleted]

Re: Stunned by Go

#27

Post by f2f »

for those not familiar with Go, here's the problem translated in C terms: "I passed a pointer to your function and it called free() on it. how dare you!"

Re: Stunned by Go

#28

Post by BarkMore »

tux21b wrote: post #21
BarkMore wrote: post #6

This issue was recently discussed on the development mail list: https://groups.google.com/d/msg/golang-dev/o9i_SbGRrzI/gWvnB... The fix is to document that Close is called: https://codereview.appspot.com/11432044/

Yes, Roger Peppe, one of the Go contributors, had exactly the same issue, but luckily Brad and Russ, two core devs, were able to solve the mystery immediately and updated the documentation. It's now quite funny to read a blog post from someone completely different (Tim Penhey) who had encountered and solved the same issue with exactly the same usecase on the very same day, complaining about Go without even mentioning…

Roger Peppe and Tim Penhey both work on Juju at Canonical. One of them wrote to the mail list regarding the issue that they encountered. The other vented his frustration on his personal blog.

Re: Stunned by Go

#29

Post by enneff »

tux21b wrote: post #24
thirsteh wrote: post #22

Earlier quoted context omitted.

That is pretty funny, but it doesn't really change anything. It's unfortunate that it called Close() without at least giving proper notice, and most people will probably agree that in a perfect world where we could start over without breaking APIs, the implementation would be different.

I was just criticizing the publishing skills of some people... The problem itself is unfortunate and I am personally not a huge fan of the "no API changes" philosophy participated by the Go team. I can understand the reasons behind it, but it's still hard to read several CLs per day that are abandoned or done differently (in a non-optimal way) because of this contract.

It's much better for the core team to compromise a little than force everyone to update their code all the time.

In particular, small semantic changes that can't be caught statically will just break people's code with no warning whatsoever. That's bad.

Re: Stunned by Go

#30

Post by thirsteh »

f2f wrote: post #27

for those not familiar with Go, here's the problem translated in C terms: "I passed a pointer to your function and it called free() on it. how dare you!"

or "I passed an fp to your function, and you called close() on it. How dare you!?" :)
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