Skip undefined protocol silently.

[kkazuo]

This can happen when you defines the protocol but does not exist class that implement it.

[kkazuo]

I have multiple app targets.
One target contains a class that implement the protocol, another targets does not.
So I can build two little different apps.
Is this wrong idea?

[AlexDenisov]

@kkazuo, could you tell us how do you use this protocol?
Unknown protocol is an edge case, so BM should stop executing to notify user that something went wrong, on the other hand it's not critical, so we can just skip this step with some extra logging...

@0xc010d, what do you think?

[kkazuo]

The build target A and B has linking this class:

@interface X : NSObject
@property (weak, nonatomic) id<MyProtocol> myDelegate;
@end

@implementation X
- (void)doSomething
{
  id delegate = self.myDelegate;
  if ([delegate respondsToProtocol:@protocol(MyProtocol)]) {
    [delegate anProtocolMethod];
  }
}
@end

Only target A has linking a class that implements MyProtocol.
So target B's myDelegate is always nil. An nil delegate is no problem.

I can escape crashing BloodMagic with dummy class that implements MyProtocol.

@interface DoesNotUseAnywhereClass : NSObject <MyProtocol>
@end
@implementation
- (void)anProtocolMethod
{
  // blank, because does not instanciate this class anywhere.
}
@end

Is this a preferred workaround?

[0xc010d]

Dummy class doesn't sound as a proper workaround, of course. I'll investigate it tomorrow.
Do you #import the header with that protocol definition?

Seems like we've already had similar issue, please check if it's not the same in your case: #9 (comment)

[0xc010d]

@kkazuo I think that might've been the issue. But, just to close that topic, could you please modify your pull request so it would be like that:

        if (!protocol) {
            NSLog(@"BloodMagic: Protocol %s hasn't been found. Please check if you include the header with that protocol description in your .m file", protocolName.c_str());
            continue;
        }

[AlexDenisov]

Totally agree with @0xc010d.

[kkazuo]

I made sample project.
https://github.com/kkazuo/SampleBloodMagic

And I found another workaround.
https://github.com/kkazuo/SampleBloodMagic/blob/master/Sample/OBIViewController.m#L29

[0xc010d]

Ok.. We might need to do a further investigation of that.

@kkazuo thank you for the finding!

[kkazuo]

Thank you for the discussion!

[AlexDenisov]

@kkazuo, finally I've merged this one. Thank you!