From: Meino Christian Cramer <Meino.Cramer@...>
Date: 2003-09-13T09:44:02+09:00
Subject: Re: Mthod redefinition

From: Austin Ziegler <austin@halostatue.ca>
Subject: Re: Mthod redefinition
Date: Sat, 13 Sep 2003 07:38:09 +0900

Hi 

 Thank you for the explanation of duck typing !
 Now I have understood, what these little ducks have to do with ruby
 programming.
 
 Would it be correct if I would say: Duck typing is more or less
 equal to providing the code for calling the "same" method of
 different signatures be hand while C++ and other OOP-languages will
 do this automagically while compiling the code ?

 Kind regards,
 Meino



> Ferenc's code does, more or less, what Ryan Pavlik's StrongTyping module 
> does.
> 
> However, with the exception of nil testing, you may feel more comfortable 
> with duck typing.
> 
> For your simple case, it might be:
> 
> class Bar
>   def foo(arg = nil)
>     return "Who gives no input will get no output." if arg.nil?
>     return "One gives me #{arg}."
>   end
> end
> 
> arg is, of course, not limited to integers at this point. The question would 
> then become what is it that you wish to do with integers that you need the 
> value? 
> 
> Duck typing is based mostly on realising what sort of operations you want to 
> do with the object and testing for those operations, rather than testing for 
> the class. As Dave is fond of saying: type and class aren't the same.
> 
> -austin
> --
> austin ziegler    * austin@halostatue.ca * Toronto, ON, Canada
> software designer * pragmatic programmer * 2003.09.12
>                                          * 18.29.32
> 
> 
> 
> 
>