> On Jul 8, 2017, at 09:46, Ivan Vučica <[email protected]> wrote: > > "id" is in general the "don't ask me, I know what I'm doing" type. > > So in theory, you could be getting no warning at all. > > That you get a warning at all is clang playing smart and saying "absolutely > nowhere, in any of the types that I saw in this compilation unit, did I see > this method". > > If you called any method known in any class (e.g. in any class defined in a > header you included) you'd also not get a warning. > > If you called a method that is defined in another file without including the > header, you'd get the same compile time warning even though the code would > work. > > Let me know if this is unclear and I'll try to rephrase – I know this is not > the clearest way to explain it :)
Thanks Ivan, that explains it! Mystery solved :) Very helpful behavior for using id in a codebase that the compiler sees in its entirety. Patryk > >> On July 8, 2017 4:04:29 PM GMT+01:00, Patryk Laurent <[email protected]> wrote: >> Hello, >> >> While experimenting with distributed objects, I noticed that the count >> method can be called on an id but I cannot just call any arbitrary method on >> id (e.g., a made-up "countx" method). >> Why doesn't calling count on an id generate a compiler >> warning/error-when-using-ARC? >> It seems the count method is accorded some special status compared to an >> arbitrary method like "countx"... how does this work? >> >> Code example including the somehow-working [id count] (but erroring other >> cases, as expected) are shown below. >> >> Thank you, >> Patryk >> >> >> #import <Foundation/Foundation.h> >> >> int main() { >> id one = [[NSObject alloc] init]; >> NSObject* two = [[NSObject alloc] init]; >> [one count]; >> [one countx]; >> [two count]; >> [two countx]; >> return 0; >> } >> >> When compiled with ARC: >> >> >> blessed_methods.m:9:10: warning: instance method '-countx' not found (return >> type defaults to 'id'); did you mean >> '-count'? [-Wobjc-method-access] >> [one countx]; >> ^~~~~~ >> count >> blessed_methods.m:10:10: warning: 'NSObject' may not respond to 'count' >> [two count]; >> ~~~ ^ >> blessed_methods.m:11:10: warning: instance method '-countx' not found >> (return type defaults to 'id') >> [-Wobjc-method-access] >> [two countx]; >> ^~~~~~ >> >> >> > > -- > Sent from my Android device with K-9 Mail. Please excuse my brevity.
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