[erlang-questions] Erlang 21, Stability and the murder of an innocent Statemachine

[Mahesh Paolini-Subramanya]

To echo Heinz's point, is there a *reason* for the deprecation?

Enquiring minds want to know...



On Fri, May 4, 2018 at 8:29 AM, Oliver Korpilla <oliver.korpilla@REDACTED>
wrote:

> Ah yes, dependencies! I see your problem now.
>
> We're using gen_statem for a test framework written in elixir for
> telecoms. The FSM has been the least of our problems.
>
> I'm always amazed at the range of Erlang versions still in use. I keep
> forgetting that.
>
> Oliver
>
>
> On May 4, 2018 8:25:35 AM EDT, "Heinz N. Gies" <heinz@REDACTED> wrote:
>>
>> Hi Oliver,
>> I am not advocating to forbid migrating code to gen_statem when the
>> maintainer feels it is an improvement for their code. I’m advocating for
>> not forcing maintainers doing so for no reason.
>>
>> Karolis brought up another very good point I didn’t even think about.
>> Code written with gen_statem will not be able to run on older erlang
>> releases. While that’s probably not a issue on your own code where you
>> control the releases completely it’s a nightmare for open source and
>> libraries.
>>
>>
>> On 4. May 2018, at 14:12, Oliver Korpilla <Oliver.Korpilla@REDACTED> wrote:
>>
>> Except for the init bug in 19.0 (which our infrastructure was fixed on
>> for a long time) we found migrating to gen_statem a painless experience
>> with decent improvements. But maybe we simply use a different or limited
>> feature set?
>>
>> Oliver
>>
>> On May 4, 2018 8:03:11 AM EDT, "Heinz N. Gies" <heinz@REDACTED>
>> wrote:
>>>
>>> I have thought of that but I don’t think that’s a real option.
>>> Deprication warnings are important, this would turn all of them off which
>>> doesn’t help code quality. I want to know if something is deprecated and
>>> fix it in most cases. But as Karolis pointed out, it’s easy for a function
>>> or two but for a whole behaviour it’s nearly impossible.
>>>
>>> It basically creates two erlang worlds, pre-statem and post-statem.
>>>
>>> The stack trace is not great but it’s not as bad, it’s somewhat possible
>>> to just wrap the whole function calling it into a ifdef and call it a day.
>>> Not great it still is a decent amount of code duplication but it’s
>>> possible. https://github.com/Kyorai/clique/commit/
>>> b0e89de3cbb56396b59a1023903c7259ec2ef145#diff-
>>> 7a19efbe2afedfb64aa7ec6690e9a13e would be an example. It’s more
>>> annoying then other changes but not nearly as bad as the gen_fsm
>>>
>>> On 4. May 2018, at 13:58, Roger Lipscombe <roger@REDACTED>
>>> wrote:
>>>
>>> On 4 May 2018 at 12:07, Karolis Petrauskas <k.petrauskas@REDACTED>
>>> wrote:
>>>
>>>> I agree with Heinz. The deprecation of gen_fsm forced me to stuck on
>>>> OTP 19 and I dont see any reasonable path to upgrade.
>>>>
>>>
>>> We upgraded successfully to OTP 20 (and compiled against OTP 21) by
>>> simply adding the following to the top of our gen_fsm modules:
>>>
>>> -compile([nowarn_deprecated_function]).  % gen_fsm is deprecated; use
>>> gen_statem
>>>
>>> It'll be a problem when gen_fsm is *removed*, but until then, we'll
>>> stick with this.
>>>
>>>
>>>
>> --
>> Sent from my Android device with K-9 Mail. Please excuse my brevity.
>>
>>
>>
> --
> Sent from my Android device with K-9 Mail. Please excuse my brevity.
>
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