[erlang-questions] -define

Ulf Wiger <>
Fri Feb 19 00:56:29 CET 2010

Robert Virding wrote:
> It is a backwards incompatible change. You have suddenly made a
> change which may break old legal code. This is really no difference
> to making a syntax change in the language. In this case it doesn't
> really matter how justified and right the change is.

There are different kinds of breakage though.
This change would cause a compilation error, which is
common to begin with (at least when I'm programming), of
a sort that is unlikely to hit you unless you're doing
something very weird and "clever", and has a very simple fix.
This is very different from a change that modifies runtime
semantics in a subtle way.

>> We should not stop being afraid of doing such changes as they are
>> clear improvements both for the language, the various tools for it,
>> and for the community in general.
> Oh, I agree but I have also had the pack after me for suggesting 
> backwards incompatible changes so I am prepared.

I know. I even remember hounding you at times, and at least once
even for making a change that /was/ BW compatible, but twice as
slow as the original code (albeit adnmittedly more elegant). :)

Ulf W
Ulf Wiger
CTO, Erlang Solutions Ltd, formerly Erlang Training & Consulting Ltd



Since January 1st 2010 Erlang Training and Consulting Ltd. has become ERLANG SOLUTIONS LTD.


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