I’ve moved some method declarations out of the @interface block into a @protocol block for Objective-C++ issues (long story). I have a file with just

@protocol WrapperProtocol

… some method declarations …

• (float*)descriptorOfPixels:(unsigned char *)I withHeight:(int)H andWidth:(int)W numChannels:(int)numChan atPoint:(NSPoint)P;

@end

When compiling this I get “error: parse error before ‘(‘ token”. This never happened when the declaration was in the interface block. Now if I change the “I” (letter ‘eye’ not number one) to “pixels” or “J” or seemingly anything else i.e.

@protocol WrapperProtocol

… some method declarations …

• (float*)descriptorOfPixels:(unsigned char *)notI withHeight:(int)H andWidth:(int)W numChannels:(int)numChan atPoint:(NSPoint)P;

@end

everything compiles just fine. Am I missing something painfully obvious (not for the first time)? Is the compiler encouraging me to choose more descriptive variable names? Obviously I can live with this, but any insight would be appreciated.

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Preprocess the file. I bet I is #defined to something that’s screwing up the compiler.