Re: why doesn't the compiler complain?
Re: why doesn't the compiler complain?
- Subject: Re: why doesn't the compiler complain?
- From: Matt Neuburg <email@hidden>
- Date: Mon, 26 Apr 2010 15:45:15 -0700
- Thread-topic: why doesn't the compiler complain?
On or about 4/26/10 1:22 PM, thus spake "Greg Parker" <email@hidden>:
> On Apr 26, 2010, at 1:01 PM, Matt Neuburg wrote:
>> Here's my test:
>> MyClass:
>> - (void) tryme: (NSString*) s;
>> MyClass2:
>> - (void) tryme: (NSArray*) s;
>> MyClass* thing = [[MyClass alloc] init];
>> NSString* s = @"Howdy";
>> [(id)thing tryme: s];
>>
> In this test, the mismatch is an NSString* parameter vs an NSArray* parameter.
> That mismatch is "safe": the compiled code for the call site looks the same
> either way. The compiler does not warn about this by default.
Thanks for this extensive reply; it taught me a lot.
Here's something interesting. If I reverse the declaration order of MyClass
and MyClass2, like this:
>> MyClass2:
>> - (void) tryme: (NSArray*) s;
>> MyClass:
>> - (void) tryme: (NSString*) s;
>> MyClass* thing = [[MyClass alloc] init];
>> NSString* s = @"Howdy";
>> [(id)thing tryme: s];
...Now the compiler *does* complain about that last line - it ways I'm
passing a string when an array was expected.
So I guess the compiler treats the *first* declaration of a method
name-and-signature that it encounters as the "real" one.
Now, that's okay, I guess (especially since there's a warning I can turn on
to detect even this level of conflict - thanks for explaining about that),
as long as the compiler is correctly foreshadowing the behavior of the
runtime. I take it from what you say about the compiled code being the same
that it is... m.
--
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