behaviours

[Wiger Ulf]

"Per Bergqvist", <per@REDACTED>, wrote:

> some questions regarding behaviours
> 
> 1) a few modules requests multiple behaviours.
>    what is the purpose of this ?

Laziness.  ;-)

You can, for example, combine gen_server and gen_event,
or gen_server and supervisor in one module, but this tricks
the linter, confuses the reader, and is in general a bad idea IMO.
 
> 2) in megaco and mnesia user defined behaviours are requested
>    but the target modules does not define the behaviour_info.
>    why ?

Back in the old days, you could not define your own behaviour
without hacking some OTP code. I vaguely recall mnesia providing
a "quasi behaviour", which wasn't really a known behaviour, but 
well could have been.

My guess is that the behaviour_info/1 function has not been added
yet, since the option to do so is a fairly recent addition.

/Uffe