20 Feb
2009
20 Feb
'09
5:05 p.m.
On 02/20/2009 04:54 PM, Henning Westerholt wrote:
On Friday 20 February 2009, Andrei Pelinescu-Onciul
wrote:
this is because the most of PVs have the string value as
well.
However, I consider that misleading, although I worked a lot the switch.
It was planned to fix as the PV callbacks had a parameter for flags.
I would prefer single type case value, and report errors at startup - it
is easier to check and optimize. It is better to use a transformation to
convert the value to a specific type (e.g., {s.int}).
Cheers,
Daniel
[..]
This would only make sense if we use match() for strings and switch()
for ints. Otherwise it would be too confusing.
Anyway I don't think the amount of details of the configuration language
is ever a problem, as long as one gets meaningful error messages when
checking the config (and before ser startup).
Hi Andrei,
the amount of detail in the config language is IMHO important. The developers
must document and test every single statement. Every user must read, learn
and memorize each statement too.
I regulary need to check the documentation for some special cases in the
config when i get asked for a review of some changes a co-worker did, because
he still feel not completely confortable after years of administrating SER*
systems. During all the time i spend on user channels i really rarely heard
the that our server is to slow (only when some real bottlenecks were
involved, like DB), the common complain is that the learning curve is too
steep. Perhaps i'm lazy, but i'd not say that everybody out there is it
too. ;-)
(1) -
could be changed in some cases (e.g. string case with some int
label allowed, which could be automatically converted to string), but I
think it would too confusing and I disallowed it (in general having
mixed types in a switch() are 99% an error).
I would suggest to convert numbers to strings in this case
automatically.
For most people things get more confusing with the increasing amount of
details they have to remember about the configuration language.
The other approaches trade-off less config
details for guessing what the
user intended, which IMO is much more dangerous. Is much better to get
meaningful errors when running ser -cf ... , then getting unexpected
behaviour at runtime (a very good example for this are typed variables
vs. untyped ones or operators that try to guess the type and assume the
user made the right choice).
I just checked in kamailio, we don't throw an error if one mix strings and
ints in a switch case. We also check for a correct type of an integer in a
mixed expression, e.g. if its a valid int value. I don't think that we
convert them implicitly, as many pseudo-variables hold internally both a
string and a integer value, so mixed expression will work just as intended in
most cases.
Cheers,
Henning
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--
Daniel-Constantin Mierla
http://www.asipto.com