[erlang-questions] (Non)Parametrized modules, inheritance, and R15B02 issues?

Jesper Louis Andersen <>
Sun Oct 7 19:41:59 CEST 2012

On Oct 7, 2012, at 12:32 PM, Tomas Morstein <> wrote:

> Hello,
> We wanted to upgrade our development environment to R15B02
> and ended up with a problem of different inheritance behaviour:
>  https://gist.github.com/3846164

This is quite interesting from a perspective of parameterized modules in general. They are not part of the language standard, but they are kept around since people use it. Now, since it is not part of the language standard and an experimental feature, it is subject to change without warning. You just hit such a problem.

Here is what may be wrong, one thing at a time:

* The code you present really *is* undefined behaviour. It should never have been accepted in the first place and you shouldn't write code like that. We don't know since there is no "right" specification here.

* The code works incorrectly, but the regression was not caught by the test suite.

* Parametertized modules are experimental, you are on your own and must adapt to the change when it happens.

* The code has a well-defined behaviour, but it was never made formal in the way the code generator works on these modules.

And so on. I don't know what the correct stance is to take here - but perhaps either Richard or the OTP might know what is right to do.

Jesper Louis Andersen
  Erlang Solutions Ltd., Copenhagen

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