# Type specific operator **URL:** \ **Category:** Ruby\ **Created:** [July 9, 2008, 9:05am UTC](https://www.ruby-forum.com/t/type-specific-operator/142563 "2008-07-09T09:05:12Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![Amitraj\_singh\_C](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/53a042/32.png) [@Amitraj\_singh\_C](https://www.ruby-forum.com/u/Amitraj_singh_C)\ **Post date:** [July 9, 2008, 9:05am UTC](https://www.ruby-forum.com/t/type-specific-operator/142563/1 "2008-07-09T09:05:12Z")
Hi all, Ruby is a dynamically typed language so it checks at run time the type of the variable and calls corresponding operator. For example “x + y” will be checked for type of x and y if both will be fixnum then corresponding addition action will be performed if both are strings the corresponding appending action will be performed. My question is" Is there any type specific operator facility available in ruby? If somehow we can infer the type of the variables then we can directly use those specific operators. I am not aware about any such operator. IF there is any please give me the references. Thanks amitraj ---
**Author:** ![Amitraj\_singh\_C](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/53a042/32.png) [@Amitraj\_singh\_C](https://www.ruby-forum.com/u/Amitraj_singh_C)\ **Post date:** [July 9, 2008, 9:14am UTC](https://www.ruby-forum.com/t/type-specific-operator/142563/2 "2008-07-09T09:14:06Z")
> Is there any type specific operator facility available in ruby? You can overload operators on specific classes if you want custom behaviour: class Foo attr\_reader :size def initialize(n) @size = n end def +(other) Foo.new(@size + other.size) end end Foo.new(9) + Foo.new(3) # =\> #\ ---
**Author:** ![Amitraj\_singh\_C](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/53a042/32.png) [@Amitraj\_singh\_C](https://www.ruby-forum.com/u/Amitraj_singh_C)\ **Post date:** [July 9, 2008, 9:26am UTC](https://www.ruby-forum.com/t/type-specific-operator/142563/3 "2008-07-09T09:26:59Z")
On Wednesday 09 July 2008, Amitraj singh Chouhan wrote: > there is any please give me the references. > > Thanks > amitraj I’m not sure I undestand correctly what you mean, but I think you have a wrong idea of how operators work in ruby. Most operators are simply shortcuts for method calls, so that, for example 1 + 3 is translated by the ruby interpreter to 1.+(3) This means that, when ruby sees the expression 1 + 3, it tries to call the + method on the 1 object passing as argument the 3 object. If you write something like: 1 + ‘a’ ruby will try to pass ‘a’ as argument to the + method of 1. But since that method can only handle objects of class Numeric or objects which have a coerce method, and strings don’t have it, it raises an exception. If you want to define operators for your own classes, you simply need to define the corresponding method: class C attr\_reader :x def initialize x @x = x end def +(other) case other when Integer then return C.new other + @x when C then C.new @x + other.x else raise ArgumentError,“You can’t add an object of class #{other.class}” end end end c = C.new 3 c1 = c + 2 puts c1.x c2 = c + C.new(5) puts c2.x c + ‘a’ The above code gives: 5 8 ArgumentError,"You can’t add an object of class String (note that doing 1+c would raise a TypeError exception, since in this case the method call would be 1.+©, instead of c.+(1), and that Integer#+ doesn’t know how to handle instances of class C). I hope this helps Stefano ---
**Author:** ![Amitraj\_singh\_C](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/53a042/32.png) [@Amitraj\_singh\_C](https://www.ruby-forum.com/u/Amitraj_singh_C)\ **Post date:** [July 9, 2008, 10:28am UTC](https://www.ruby-forum.com/t/type-specific-operator/142563/4 "2008-07-09T10:28:19Z")
Thanks for making me correct. But as in case of x + y it gets converted to x.+(y). So here the type of x must be known(that is what I mean by checking type of x) and also to execute + method of x’s class and to pass it argument y, type of y must be known(that is what I mean by checking the type of y). These checkings will be done at run time. My question is if we have an Idea about the type of x and y initially(at the time of writing the program) can we eliminate these type checks. I mean is there any operator or method call that will directly treat x and y as fixnum. i.e. something like int+(x,y) //specific function for adding two integer string+(x,y) //specific function for appending two strings or any thing like that which will directly treat x and y as variables known types I hope you will be getting my point. Please give me the details if there is any such thing in ruby. Thanks amitraj ---
**Author:** ![Amitraj\_singh\_C](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/53a042/32.png) [@Amitraj\_singh\_C](https://www.ruby-forum.com/u/Amitraj_singh_C)\ **Post date:** [July 9, 2008, 10:59am UTC](https://www.ruby-forum.com/t/type-specific-operator/142563/5 "2008-07-09T10:59:45Z")
On Wed, Jul 9, 2008 at 10:24 AM, Amitraj singh Chouhan [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > Thanks for making me correct. But as in case of x + y it gets converted > to x.+(y). So here the type of x must be known(that is what I mean by > checking type of x) and also to execute + method of x’s class and to > pass it argument y, type of y must be known(that is what I mean by > checking the type of y). > You can call x.class but believe me that will not give you an exact > idea where the message :+ will be intercepted. > These checkings will be done at run time. > I would not call it checkings, I would call it method dispatch. AFAIK > the message will be dispatched up the ancestor chain until an > implementing method is found, if none is found the same search is > repeated for #method\_missing, however… > My question is if we have an > Idea about the type of x and y initially(at the time of writing the > program) can we eliminate these type checks. I mean is there any > operator or method call that will directly treat x and y as fixnum. i.e. > something like > int+(x,y) //specific function for adding two > integer > string+(x,y) //specific function for appending > two strings > or any thing like that which will directly trea > I believe that people are working on such optimizations via dynamic > code analysis but really I am not good enough to give any detailed > information about this :(. ## Maybe you should have a closer look into jruby. HTH Robert [http://ruby-smalltalk.blogspot.com/](http://ruby-smalltalk.blogspot.com/) * * * AALST (n.) One who changes his name to be further to the front D.Adams; The Meaning of LIFF ---
**Author:** ![Amitraj\_singh\_C](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/53a042/32.png) [@Amitraj\_singh\_C](https://www.ruby-forum.com/u/Amitraj_singh_C)\ **Post date:** [July 9, 2008, 11:10am UTC](https://www.ruby-forum.com/t/type-specific-operator/142563/6 "2008-07-09T11:10:57Z")
Amitraj singh Chouhan wrote: > These checkings will be done at run time. My question is if we have an > Idea about the type of x and y initially(at the time of writing the > program) can we eliminate these type checks. Why would you want to? Are you trying to solve a specific problem, or understand conceptually? Are you assuming some sort of efficiency gain by doing as you would like? > I mean is there any > operator or method call that will directly treat x and y as fixnum. i.e. > something like > int+(x,y) //specific function for adding two > integer > string+(x,y) //specific function for appending > two strings > or any thing like that which will directly treat x and y as variables > known types > Objects such as Fixnum and String have a + method that they respond to: > > > x=1 > > =\> 1 > > > x.respond\_to?("+") > > =\> true > > or not: > > > h= {:a =\>1} > > =\> {:a=\>1} > > > h2 = {:b =\> “foo”} > > =\> {:b=\>“foo”} > > > h.respond\_to?("+") > > =\> false > > > new\_h = h+h2 > > NoMethodError: undefined method `+’ for {:a=\>1}:Hash > > from (irb):3 This is the idea behind DuckTyping. It doesn’t matter the type of the object, so long as it responds to a specific message, all is well. As you see above, you can investigate for yourself ahead of time if the receiver responds to a particular message with respond\_to?, but that doesn’t really accomplish what you are looking for, specifically, in terms of the Ruby interpreter doing it’s job at runtime. Howard ---
**Author:** ![Amitraj\_singh\_C](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/53a042/32.png) [@Amitraj\_singh\_C](https://www.ruby-forum.com/u/Amitraj_singh_C)\ **Post date:** [July 9, 2008, 2:43pm UTC](https://www.ruby-forum.com/t/type-specific-operator/142563/7 "2008-07-09T14:43:34Z")
Hajime-mashite \> Amitraj-san I’m not sure I got your point of problem, but the discussion so far reminds me of a conceptual problem; in Smalltalk(and in ruby, nowadays), (1 + ‘a’) and (‘a’ + 1) could give different answers. These language isn’t ‘symmetrical’ in such point. So… On 2008/07/09, at 18:51, Amitraj singh Chouhan wrote: > not any specific program but any program which uses such operators. if it’s your problem for daily life, You could give a try on CLOS: a OOL in Lisp fashion. Or CLOS is not practical for you, You could define Classes in Ruby to establish Sets --in mathematical sense-- in which your Operators of concern go with Commutability. # Ruby is in a spirits of Do-It-YourSelf, I guess. oop. moderate choice is there: Smalltalk. The choices are up to you. ======================= 2 bits thinking helps 66.7% Shindo Motoaki (Motoakira) # 21, Higashi-Kurayoshi machi Yonago City, Tottori Pref. 683-0815, Japan TEL 81-859-33-7431/81-90-7593-3585 [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) ---
**Author:** ![Amitraj\_singh\_C](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/53a042/32.png) [@Amitraj\_singh\_C](https://www.ruby-forum.com/u/Amitraj_singh_C)\ **Post date:** [July 9, 2008, 11:55am UTC](https://www.ruby-forum.com/t/type-specific-operator/142563/8 "2008-07-09T11:55:42Z")
> Why would you want to? Are you trying to solve a specific problem, or > understand conceptually? Are you assuming some sort of efficiency gain > by doing as you would like? > Yes I would like to optimize the program, not any specific program but > any program which uses such operators. Can I get some reference for the working of the interpreter, I mean how it process the given ruby program. Is there any link or document which describes the step by step actions performed by interpreter and the description of those steps. -amitraj