CODEWITHSUNDEEP
objective-c
cppforlife
cppforlife

Reputation: 83

dynamic properties in objective c

I found out Objective-C object properties can be marked as @dynamic to let compiler know that implementation will be available at runtime. I'd like to know if there is a way to tell the compiler that all properties on an object are dynamic without explicitly specifying them one-by-one (I don't have a list of properties up front). I know that this would not be a problem if I would just use [object something] but for stylistic purposes I want to use object.something syntax.

I'm fairly sure that it's not possible to do that but I'd like someone to confirm that. Since this is not for production use solution can involve anything you can imagine.

Thanks.

Additional info:

Example:

@interface MagicalClass : NSObject
// property 'something' is not defined!
@end

@implementation MagicalClass
- (NSMethodSignature *)methodSignatureForSelector:(SEL)aSelector { ... }
- (void)forwardInvocation:(NSInvocation *)anInvocation { ... }
@end

MagicalClass *obj = [[MagicalClass alloc] init];
[obj something]; // compiler warning
obj.something; // compiler error

Upvotes: 5

Views: 2284

Answers (3)

Chuck
Chuck

Reputation: 237060

This really doesn't work with declared properties. The whole point of them is that you declare upfront what your properties are and how you interact with them. If you don't have any to declare, then you don't have any declared properties.

Unfortunately, it also doesn't work well with plain messages, although it can work better than dot syntax. Objective-C's static type checking will throw a hissy-fit of warnings, and if any of the properties are of non-object types, it might not be able to generate the correct calling code.

This kind of thing is common in languages like Python and Ruby where things don't have to be declared, but it just doesn't mesh well with Objective-C. In Objective-C, accessing arbitrary attributes is generally done with strings (cf. Key-Value Coding and NSAttributedString).

Upvotes: 4

andyvn22
andyvn22

Reputation: 14824

I don't believe this is possible. If you use the id type, you may be able to send undeclared messages, but dot syntax really relies on knowing about your specific accessors.

Upvotes: 2

Thomas Müller
Thomas Müller

Reputation: 15635

I haven't tried this, but if you provide a getter and setter, does Xcode still want the @synthesize or @dynamic directive?

So if you property is called something, implement -setSomething: and -something.

Upvotes: 0

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