[erlang-questions] Trace-Driven Development

Ulf Wiger <>
Mon Jun 4 08:52:46 CEST 2012


4 jun 2012 kl. 06:52 skrev Michael Turner <>:

> I'm a little embarrassed to be doing a "reply all" on this message,
> because I'm (still) such a stop-start Erlang newbie. What compensates
> for the mortification, however, is passages like the following, which
> suggest I'm hardly the only one who should be embarrassed:
> 
> "Erlang tracing is a seething pile of pain that involves reasonably
> complex knowledge of clever ports, tracing return formats, and
> specialized tracing MatchSpecs (which are really their own special
> kind of hell). The tracing mechanism is very powerful indeed, but it
> can be hard to grasp."
> 
> Obviously, that kind of statement has no place in the official
> documentation of a professional product. 

You are absolutely right about that.

> I started using seq_trace. It has its own documentation problems, of
> course. For example: since seq_trace is an implementation of Lamport
> clocks, you should *say* somewhere (like, in the first paragraph,
> maybe?) that it's an implementation of Lamport clocks. Don't make it
> sound like your own invention. 

Actually, I believe it is more correct to say that it's based on the "forlopp trace" thst exists in Ericsson's AXE switches (using the proprietary language PLEX). Whether forlopp trace was based on Lamport clocks, I couldn't say. I don't know when it was introduced in the AXE (Lamport published his paper in 1978, the same year that the first digital AXE was taken into service), and to what extent it was informed by Lamport's work.

Anyway, not noting in the docs that sequence trace mimicks AXE's forlopp trace seems forgiveable, since very few people would know what that is. :)

See e.g. http://es.scribd.com/mobile/doc/83784121, starting at page 109.

BR,
Ulf W



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