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Because of the implicit thing! The api designer doesn't have to write the interface, you can do it yourself. As long as naming conventions are kept to and the s
by arnehormann 12y ago
Because of the implicit thing! The api designer doesn't have to write the interface, you can do it yourself. As long as naming conventions are kept to and the signature matches, you can apply this anywhere.
Imagine a close() interface in Java. There isn't one - but having a try {...} finally { x.close(); } can be very useful sometimes. But having interface graphs made of granular interfaces makes everything slow and causes a lot of complexity when you try to think about your type hierarchy. That's why interfaces always just grow and you can't use them any longer because other classes only implement part of the api. Something usable for all of awt, swing, file handling, random foreign libraries? Unthinkable. Also, adding something in a later release (like CharSequence in 1.4) can have a wide ranging impact and requires you to change a lot of code.
In Go, you just add an interface from the union set of multiple structs api - and you can use it. No matter who wrote those structs. The value is enormous. Think of it as something like dependency injection at compile time.
- raverbashing 12y agoLike duck typing?
- LBarret 12y agoI suspect this is like duck typing with some verification before compilation : the compiler checks that the object sent as parameter implements the correct interface.
- diroussel 12y agoIt's called structural typing.
- kaoD 12y agoSo, compile-time duck typing.
- tel 12y agoIn the same Formula 1 is performance go-karting.
- coldtea 12y agoNo, structural typing. It has a name already.
- dllthomas 12y agoSo, wikipedia says (http://en.wikipedia.org/wiki/Duck_typing#Structural_type_systems http://en.wikipedia.org/wiki/Duck_typing#Structural_type_sys...): "Duck typing is similar to but distinct from structural typing. Structural typing is a static typing system that determines type compatibility and equivalence by a type's structure, whereas duck typing is dynamic and determines type compatibility by only that part of a type's structure that is accessed during run time." So it sounds like "duck typing" is defined in terms of run-time semantics. I guess you might be able to have genuine "compile-time duck typing" in a dependently typed language, which could be a good reason to preserve the distinction. Otherwise, yes, they are certainly similar.
- pjmlp 12y ago> Because of the implicit thing! Known as structural typing and available in most modern languages.
- icebraining 12y agoavailable in most modern languages Well, "modern" is an ill-defined concept. As far as I'm aware, structural typing is not really that common, is it? Besides OCaml and Scala, is there any relevant (used outside of academia) language that supports it?
- pjmlp 12y agoD and C++ templates for example. F# also supports it, given its ML linage. C# tricks with dynamic, although in this case it is dynamic typing, so not really the same thing.
- seabee 12y agoThe disadvantage of C++ templates is the structural type is implicit - you only know if the input object satisfies the type if you read the documentation, code, or can decipher the error message that occurs if it didn't. Concepts would have fixed this, but we don't have concepts and maybe never will!
- pjmlp 12y ago> Concepts would have fixed this, but we don't have concepts and maybe never will! enable_if and type traits are a workaround for the time being. Concepts lite will definitely be in the next revision.
- losvedir 12y agoWould rust's "traits" count as structural typing? (I know Rust may not count as "relevant (used outside of academia)" yet, but maybe in the future.)
- tel 12y ago
- mschulze 12y ago>Imagine a close() interface in Java. There isn't one https://docs.oracle.com/javase/7/docs/api/java/lang/AutoCloseable.html https://docs.oracle.com/javase/7/docs/api/java/lang/AutoClos... You can even leave out the finally when you use an autocloseable resource. //r will be closed no matter what try(Resource r = getResource()) { } catch(SomeException e) { }
- arnehormann 12y agoMy Java is getting rusty... I read about this sometime somewhere but forgot it, thanks! I should have picked something like "String getText()", then.