[erlang-questions] case or clause
Fri Jan 9 03:14:27 CET 2009
is it more useful?
if I have:
f(a,Var) -> ok;
f(b,Var) -> 10/0;
f(c,Var) -> ok.
and call: f(b,foo)
The error message would say it failed in "f/2"
It doesn't tell me at all which one it actually failed in. Buf for a gen_*
you would know since they show the last message in, which usually lines up
with a function. But in generic library code, it always seems
hard-to-impossible to tell from the stack. I end up adding print statements
all over and re-producing to find offending function.
That being said, I actually prefer many little functions anyway as it tends
to be easier to read at a glance.
2009/1/8 Hynek Vychodil <>
> I can see one subtle difference between mane short functions and less
> longer. If error occurred, back-trace is more useful for shorter functions.
> 2009/1/8 Robert Virding <>
>> This thread is also a comment to an earlier question by Edward Stow <
>> 2009/1/8 Richard Carlsson <>
>>> In efficiency terms, there is no real difference. (If there is one,
>>> it should be considered a compiler problem that might be corrected
>>> at any time - do not waste your time on such microoptimizations.)
>>> Oh, and 'if' switches are no different - they're really a 'case'.
>> Just to qualify Richard's comment. There is no difference at all, in the
>> compiler function clauses are first transformed into a case.
>>> So it's mostly a matter of taste. If your switch makes sense on its
>>> own, i.e., you can give it a reasonably straightforward name, then
>>> by all means break it out as a function - it will make the code
>>> easier to read and make it easier for you to see when there is
>>> common functionality that could be reused rather than copy-pasted.
>> Sometimes I also do the opposite and use function clauses / case as a
>> means of grouping to emphasize a code structure. So while you can write:
>> foo(a, m, Z) -> ...;
>> foo(a, n, Z) -> ...;
>> foo(a, o, Z) -> ...
>> it might sometimes better clarify your intent to group function clauses
>> and write:
>> foo(a, Y, Z) ->
>> case Y of
>> a -> ...;
>> b -> ...;
>> As already noted there is no difference in efficiency. This is probably
>> not a PC thought for a functional language I sometimes feel that you can get
>> too of a good thing and have too many small functions and it can make
>> reading the whole more difficult.
>> erlang-questions mailing list
> --Hynek (Pichi) Vychodil
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