Comments on: Ruby For Java (and C#) Programmers, Part 3 - Introducing Arrays, Hashes and the typing system

By: Jules

Jules — Wed, 18 Jan 2006 16:26:48 +0000

Nice article, except:

array.each { | item | puts item.to_s }

Because:

array.each { | item | puts item }

and:

puts array

Would do exactly the same thing. Maybe:

array.each{|item| puts item.length}

But that could be:

puts array.map{|item| item.length}

In Ruby world, you’d write something as simple as possible, and that means as concise as possible most times.

And it’s often a good idea to separate the IO from the “real” code.

Really good article though. I’d like to read more about Enumerable methods, because this slightly functional module is hard to understand for Java/C# programmers. (C# is going functional too, with anonymous functions)

Keep up the good work!

By: sam newman

sam newman — Mon, 20 Jun 2005 22:41:47 +0000

Godamit! Corrections being made now….grr…

By: Chris Rimmer

Chris Rimmer — Mon, 20 Jun 2005 21:41:10 +0000

Call me Mr Picky if you want (it’s an improvement on “Chirs” at least), but I also think you mean “Naturalist”.

By: sam newman

sam newman — Mon, 20 Jun 2005 20:40:37 +0000

Yes Chirs, it certainly should :-) In an alternative universe, I’m sure there is a me who actually proof reads this stuff and runs the code snippets through irb…

By: Chris Rimmer

Chris Rimmer — Mon, 20 Jun 2005 20:17:29 +0000

Um, shouldn’t this:

array.find_all { | item | item => 8 } —> [8, 10]

be this?

array.find_all { | item | item >= 8 } —> [8, 10]

By: Sam Newman

Sam Newman — Mon, 20 Jun 2005 09:13:23 +0000

I’m not sure how they do solve the above example (and there are differences between Java generics and C++ templates) – the initial problem here is that Dog and Dog are in seperate hierarchies. The two Java solutions are either to implement a more fine-grained interface (e.g. Communicative) which defines the speak method, or to define a new base interface as I showed above. With Ruby there is no need for either. Don’t forget as well that Ruby’s type system is also dynamic – the lack of a dynamic typing system is the reason why you end up having to mess around with code generation, bytecode weaving and dynamic proxies for things like AOP, JDO and Hibernate in Java.

By: Josh Graham

Josh Graham — Mon, 20 Jun 2005 08:13:56 +0000

How do Java’s new “Generics” (like C++ Templates) solve (or not) your comparison on the Duck / Dog speak method call. I’m reckoning they do.

By: sam newman

sam newman — Sat, 18 Jun 2005 21:21:47 +0000

That’s certainly coming up Gary – although next I think I’m either going to look at string and IO handling, or I’ll be looking at map/reduce.

By: Gary Blomquist

Gary Blomquist — Fri, 17 Jun 2005 20:36:53 +0000

If you’re taking votes, I vote for “the dynamic nature of Ruby’s typing” for the next article.

By: Sam Newman

Sam Newman — Fri, 17 Jun 2005 09:06:47 +0000

Aslak – I do plan to look at API comparisons (especially IO and XML handling) although this might be in part 5. In the next part I’m either going to look at the dynamic nature of Ruby’s typing, or look at more advanced use of Hashes/Arrays and some string handling.

Oh, and thanks for stopping the typo Anjan – I really shouls stop writing this stuff late at night…