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Discussion on: The Problem with Interfaces, and how Go Fixed it

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dean profile image
Dean Bassett Author

First of all - Go isn't object oriented. It doesn't have classes, it has structs. It doesn't have methods, it has functions that operate on structs. OOP interfaces describe what a class is, but Go interfaces describe how a struct behaves.

It's okay to accidentally implement an interface, there's no sacrifice. Sure, you might make a door struct that might have a close() function, but in order to mess something up, you'd need to pass it into a method that clearly says it takes an io.Closer as an argument.

Also, these exceptions are still caught at compile time. If you pass a struct that doesnt match a specific interface to a function that requires that interface, it will throw a compile-time error that specifies which functions are missing from the struct.

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ddekany profile image
ddekany

My point didn't go though. I wasn't talking about uncaught mistakes. My concern is about how self documenting the code will be, and for what was that sacrificed. Let me try again. If a type T has a set of functions associated that satisfy the I interface, and also they behave as described in the documentation of I, then most certainly the author of T (or of the functions) has deliberately "implemented" the I interface there. Right? I mean, just how often does such thing happen by chance? If almost never, then why do the Go designers want us to not state that intent (I'm implementing I) in the language? What's the actual, practical, every day use case for "implementing without stating it"? Surely it's not that Go developers often get extremely lucky and so can avoid adapters.