Le 4 avr. 2012 à 17:57, Jens Alfke a écrit :
>
> On Apr 4, 2012, at 8:37 AM, Andreas Grosam wrote:
>
>> In a "debug" version, use NSAssert and friends (ensure Preprocessor macro
>> "NS_BLOCK_ASSERTIONS" is not defined). Use Unit tests in order to detect
>> *any* possible logic error. In a "release" version where NSAsserts and
>> friends may become no ops, this may possibly ensure that no invalid
>> parameters will be ever passed to the method.
>
> I don't think NS_BLOCK_ASSERTIONS is normally set for you in a Release build.
> Of course you can change the project settings to do so, but I don't know how
> common that is — Apple generally ships its apps and frameworks with
> assertions enabled, and I've never turned them off in anything I've written.
>
>> However, if you cannot guarantee that - or if you find this assumption too
>> hairy - the best you probably can do is:
>>
>> if (url == nil) {
>> NSLog(@"FATAL ERROR: invalid parameter in initWithURL:");
>> abort();
>> }
>
> I disagree.
> First, if the developer is turning off assertions, it's because s/he doesn't
> want the overhead (in code size and runtime) of these kinds of checks. So
> except in very unusual circumstances you should honor that and not force your
> check to happen anyway.
> Second, calling abort() is way too harsh. Call +[NSException raise:] instead.
>
> —Jens
While +[NSException raise:] is a convenient method, it is not annotated as
'noreturn' and so don't let the compiler/analyzer know about the control flow.
Using @throw does not have such issue and may prevent unexpected warnings (for
example about uninitialized variable or about missing return statement).
-- Jean-Daniel
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