# Duck Typing in other languages? **URL:** \ **Category:** Ruby\ **Created:** [August 29, 2007, 11:34am UTC](https://www.ruby-forum.com/t/duck-typing-in-other-languages/113261 "2007-08-29T11:34:36Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![quik77](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/q/dec6dc/32.png) [@quik77](https://www.ruby-forum.com/u/quik77)\ **Post date:** [August 29, 2007, 11:34am UTC](https://www.ruby-forum.com/t/duck-typing-in-other-languages/113261/1 "2007-08-29T11:34:36Z")
Heya, [http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/78502](http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/78502) is now a bit older than four years 😉 Bit long, sorry, my “real” question is on the bottom of this … anyway 🙂 I think i get that with duck typing you dont care what class/type something is. You ask it if it reponds\_to? something (and thus has a method) It sounds a bit as if classes become less important than behaviour (i think that’s a good notion anyway) and is thus a lot more flexible in general. So far so fine. When I lately asked on an IRC channel for a prototype based language, I unfortunately didn’t really get the answer I hoped for (how that language handled “duck typing”) but actually it was quickly pointed out that duck typing is used in other languages a lot too, maybe with different names )and for static languages with a bit more rigid structure). One definition that kept up was “late bound” (I admit freely, duck typing would be approximately 100x easier to understand than “late bound”, IF this refers to the same concept) Smalltalk and Self would be examples for late bound concept. Java has dynamic class loading and virtual calls (checked at class loading time and checked on interfaces) but it seems very rarely used (and, it seems you have to do a _new_ abstract class? How strange is this to create a totally new class just to get to this behavioural concept?? But then again I may be totally wrong 🙂 ) Basically it seems to boil down (for me) to message sends and a class/type “less” approach where the object just adapts to a job, instead of satisfying a compiler… 😉 Ok now to my question! What is the difference between ruby’s approach to classes and duck typing compared to prototype based languages which seem to have an even looser model (i.e. a less rigid class vs object distinction and their usage of prototypes “adapting” to a problem from the “bottom-up” ?) Ah and if I forgot something about duck typing or similar in other languages - maybe its interesting - please someone feel free to point that out! ---
**Author:** ![quik77](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/q/dec6dc/32.png) [@quik77](https://www.ruby-forum.com/u/quik77)\ **Post date:** [August 29, 2007, 12:23pm UTC](https://www.ruby-forum.com/t/duck-typing-in-other-languages/113261/2 "2007-08-29T12:23:59Z")
On 8/29/07, Marc H. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > It sounds a bit as if classes become less important than > behaviour (i think that’s a good notion anyway) and > is thus a lot more flexible in general. So far so fine. > 100% aligned > > When I lately asked on an IRC channel for a prototype based > language, I unfortunately didn’t really get the answer I hoped > for (how that language handled “duck typing”) but actually > it was quickly pointed out that duck typing is used in other > languages a lot too, maybe with different names )and for > static languages with a bit more rigid structure). > Well maybe I understand incorrectly but I would say by machanisms like > adding behavior to objects (I really like the term behavior here) > Maybe my ideas might interest you, they are expressed here: > [Smalltalking about Ruby: Classless Ruby, a Paradigm Change?](http://ruby-smalltalk.blogspot.com/2007/08/from-method-redefinition-to-anonymous.html) > you will see how I got rid of classes completely, in Ruby. > > One definition that kept up was “late bound” (I admit freely, > duck typing would be approximately 100x easier to understand > than “late bound”, IF this refers to the same concept) > I think not really, I would say late binding is extremely useful for > the agility of a language but behavior could be fixed at compile time > without any class or is\_a? concept and we still would have duck\_typing > objects, but I feel that without late binding it is less fun, maybe > not even worth it, hmm that is food for thaught. > It would be nice if we could just assume Late Binding anyway 😉 > Basically it seems to boil down (for me) to message sends > and a class/type “less” approach where the object just > adapts to a job, instead of satisfying a compiler… 😉 > Yup and in the end it might not even matter if this behavior was > created by instantiation from a class or not, maybe you should have a > look at this too: > [http://www.iam.unibe.ch/~scg/Archive/PhD/schaerli-phd.pdf](http://www.iam.unibe.ch/~scg/Archive/PhD/schaerli-phd.pdf) > It is about Traits, anyway the way how to induce behavior into objects > is a very interesting field, strictly speaking it is not 100% bound to > duck typing as long as one is not hindered by Compiletime (or even > Runtime) checks looking at labels sticked onto objects, right? Cheers Robert ---
**Author:** ![quik77](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/q/dec6dc/32.png) [@quik77](https://www.ruby-forum.com/u/quik77)\ **Post date:** [August 29, 2007, 3:35pm UTC](https://www.ruby-forum.com/t/duck-typing-in-other-languages/113261/3 "2007-08-29T15:35:41Z")
On 8/29/07, Marc H. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > Ah and if I forgot something about duck typing or similar > in other languages - maybe its interesting - please someone > feel free to point that out! Another place I’ve noticed similar functionality is with templates/generics in C++/Java. You write code that doesn’t care about the (template/generic) classes/types. You write code for objects of template/generic classes that respond to a set of methods that you use. Compared to duck-typing in ruby, the main difference is that concrete classes that you want to use for these template/generic classes must be determined at compile-time. And of course template/generic code is extremely ugly because it has to look like static typing even those the types are variable. Also, with template/generic code, the code is replicated for each class/type combination, where with duck-typing this is not needed since finding the methods occurs at run-time. ---
**Author:** ![quik77](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/q/dec6dc/32.png) [@quik77](https://www.ruby-forum.com/u/quik77)\ **Post date:** [September 6, 2007, 5:26pm UTC](https://www.ruby-forum.com/t/duck-typing-in-other-languages/113261/4 "2007-09-06T17:26:21Z")
Marc H. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > I think i get that with duck typing you dont care what > class/type something is. You ask it if it reponds\_to? > something (and thus has a method) Duck typing is not formally defined. If it means similar interfaces, it can be inferred: $ ocaml let duck ob arg = print\_int (ob#meth arg);; val duck : \< meth : 'a → int; … \> → 'a → unit = The type inference finds that ob is an object with the method meth which returns an integer. There is even polymorphism in the argument allowed. I wonder if functors qualify as duck typing on a more general level. Benedikt