[erlang-questions] FOP (was: Re: Trace-Driven Development)

Ulf Wiger <>
Fri Jun 8 11:55:05 CEST 2012


On 8 Jun 2012, at 09:19, Michael Turner wrote:

> If I submitted a patch to the seq_trace documentation so that it
> mentioned that seq_trace implements Lamport clocks, and it got
> rejected with "we're still thinking about how to work that fact in,
> maybe we'll have something in the next release," I think I'd end up
> writing Lamport to say, "Can you *believe* these people?"

Up to this point, I thought you were on a roll with clear, 
insightful and respectful discussion not least about the
problems of understanding each other in writing, and 
conveying ideas through documentation.

I can understand that certain points can get lost in a long 
and heated thread, so let me clarify a few things:

- I don't work for Ericsson (as also apparent from my sig)

- I don't vet patches on OTP. I have to submit patches like
  everyone else; sometimes they are rejected, mostly not.

- Whatever changes *I* would like to see to seq_trace, are
  my own ideas; It's been quite a while since the topic of 
  seq_trace came up in any discussions I've had with OTP,
  and then only in passing (although I *did* push for changes
  to TTB a while back that would make sequence tracing, 
  and other things, easier, and was glad to finally see the 
  changes, most of which not made by me, accepted).

In this particular case, the most relevant passage of our
long discussion should be Gustav Simonsson (who *does*
represent OTP) saying that your patch was welcome:

[Gustav:]
> +1
> 
> Especially under the "Advanced examples" section there
> is less need for brevity since users clicking on that section
> likely are prepared for multiple, possibly long, examples
> of using the Event Tracer.


Most doc- and other patches are unsolicited. I have a number
of times asked for advance feedback on the list, to get some
indication of whether it would be worth my while to put in the 
time and effort to make a patch (in those cases, changes that
affect the API and documentation). Usually, such queries
have gone unanswered, and I'm left to decide for myself 
whether I should embark on a project of writing code, test 
suites and documentation and making an argument that 
(1) the change is an improvement, (2) doesn't break 
anything, (3) doesn't confuse users who don't need the 
new feature, etc. *That* can easily amount to a week's 
worth of work, with no guarantee that it will be accepted.

In the most recent case, it was much, much more than that: 
a fairly large addition to mnesia that has been many years 
in the making, and was brought to patchworthy status only 
through the sponsorship of Klarna, and the help of Roland 
Karlsson at Erlang Solutions, since I was no longer in a 
position to complete it. That change was actually rejected 
a few times in the early stages. For the larger project, we 
visited the OTP team to present our ideas and get an 
early indication that it was a plausible approach - no 
guarantees that it would finally be accepted, but as much 
encouragement as was reasonable at the time.
http://www.erlang-factory.com/upload/presentations/601/EUC2012-009.pdf

Personally, I think that's ok. It's my idea, and others may not 
agree, or otherwise find it important. However, for everyone 
(not least on the OTP team) who spots such requests for 
early feedback: it really means a lot to get comments early 
on.

As for feedback from me, I'm just another user on the list. I 
have never been in a position to decide what goes into OTP
(well, except for being on the EEP committee). Kenneth 
has no problem rejecting my advice, although I believe he 
values it. The only concrete comments you've gotten this 
time from OTP have been words of encouragement: submit 
a patch, and it will be accepted as long as it improves the 
documentation - not a single hint that they are planning 
anything else for seq_trace. We have no reason to think 
that they are, but now would of course be a good time 
to say so then. :)

I reserve the right to give feedback with the intent of being 
helpful, but it is *not* to be interpreted as an opinion from 
the Erlang maintainers. Any such opinion must come 
straight from the OTP team, preferrably framed in such 
a way that it is clear that they are not just engaging in 
free and open debate.

There are others who are actually on the fence: Joe,
Richard Carlsson, Kostis, … who are not on the OTP
team, but deeply enough involved that it can 
sometimes be hard to make out whether they speak
for the Team or not. In case of doubt, it's best to ask
for clarification and generally assume they don't.

BR,
Ulf W

Ulf Wiger, Co-founder & Developer Advocate, Feuerlabs Inc.
http://feuerlabs.com






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