Objective-C dot notation with class methods?

Question

Note, I'm specifically referring to the fact that dot notation is being used with class methods, not instance methods. Out of curiosity, I wanted to see what would happen if I tried to use Objective-C dot notation syntax with a class method. My experiment was as follows: ``` #import <Foundation/Foundation.h> static int _value = 8; @interface Test : NSObject + (int) value; + (void) setValue:(int)value; @end @implementation Test + (int) value { return _value; } + (void) setValue:(int)value { _value = value; } @end int main(int argc, char * argv[]) { NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init]; NSLog(@"Test.value: %d", Test.value); NSLog(@"[Test value]: %d", [Test value]); Test.value = 20; NSLog(@"Test.value: %d", Test.value); NSLog(@"[Test value]: %d", [Test value]); [Test setValue:30]; NSLog(@"Test.value: %d", Test.value); NSLog(@"[Test value]: %d", [Test value]); [pool release]; return 0; } ``` I was surprised to see that this was compiled, let alone executed with what…

Accepted Answer

This is correct behavior. `foo.method` is syntactic sugar for `[foo method]`—a straight conversion with identical semantics. Similarly `foo.prop = bar` is syntactic sugar for `[foo setProp:bar]`, again with identical semantics. This transformation is implemented in the compiler. Thus you can use dot notation to call 0-parameter methods as in `foo.doSomething` instead of `[foo doSomething]`. Of course, if you do this, you are evil.

The fact that the callee is a class instance doesn't mater because in Objective-C, classes are also objects. Using dot notation on a class calls the parameterless method on that class.

Dot notation is described in the Objective-C Programming Language document.

Objective-C dot notation with class methods?

Solution

Problem