Has anyone ever done work to get Ruby to do continuations (like Seaside on Smalltalk)?
Yes, in most cases. MRI (1.8) have supported them as far as my memory reaches, Ruby 1.9 (YARV) does it, too, so does Rubinius. JRuby and IronRuby don't have continuations, and it's quite unlikely they will get them (JVM and CLR use stack-instrospection for security)
Ruby as a language supports continuations via callcc keyword. They're used, for example, to implement Generator class from standard library.
continuations on ruby-doc
Continuation-based web frameworks (like seaside, or one from Arc's std. library) seem less popular. I've found wee that claim to let you do optional continuations, but I've never used it.
As others have said already, Ruby 1.8 supports continuations.
Ruby 1.9 has not supported them for a while however. They have been added back some time this year, but most of the other Ruby interpreters (JRuby, IronRuby, etc) don't support them.
If you want your code to be usable on other platforms than the mainline Ruby, I'd suggest not using them.
Read this InfoQ article for a more comprehensive discussion on the topic.
Btw this is an example of restartable exceptions (aka conditions) implemented using continuations. I used it few times and it's a cool thing to have in a Ruby toolbox.
neverblock uses 1.9 fibers for a single threaded ruby web server
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I use Ruby from a user level and really don't deal with the internals. I have know Rubinius as 'Ruby in Ruby' which I assumed was a generalization. Recently, I got an error with Rubinius in the RubySL (no, I don't have error msg).
I started looking at RubySL and was a little surprised to see Rubinius everywhere. I really like Ruby and was just curious why Rubinius is in most of the RubySL? It seems to be used with things like locks / unlocks (such as https://github.com/rubysl/rubysl-thread/blob/2.0/lib/rubysl/thread/thread.rb ). Definitely not questioning it, just curious.
RubySL is short for Ruby Standard Library. It is a basic part of the shipped code bundle which forms what is generally known as Ruby. The standards library provides rather basic stuff you often need but which doesn't need to be part of the core language.
For example, the implementation of the Hash or Array, the language keywords, how assignment works, ... are part of the core language. These are often implemented in a language other than Ruby. MRI (the common C-Ruby) implements this mostly in C, JRuby implements this in Java. Rubinius implements this patly in C++ but mostly in Ruby itself. It can do this by bootstrapping itself from a very simple base VM and gradually adding more stuff with Ruby.
The standards library however is mostly implemented in Ruby in all implementations (with some exceptions mostly for performance reasons). Now, all Ruby implementations right now have their own implementation of the Ruby standards library which can thus differ in minor details.
Rubinius' approach to implementing a standards library was to implement it as separate gems. The idea was to one day provide a common standards library which could be used by other implementations (including MRI). This is in line with the efforts of esp. the Rubinius community to drive the RubySpec project in order to provide a common language specification and test suite for all Ruby implementations.
The RubySpec project was eventually abandoned and right now, it doesn't seem as if other Ruby implementations seem to be moving to the RubySL gems for implementing their standards library.
Thus, (and this is the TL;DR), the RubySL gems implement the Ruby Standard Library for the Rubinius project. Thus, it is expected to see the Rubinius project all over the place there: it is their code which is generally not used by other Ruby implementations.
Can anyone recommend any good multithreading / processing books / sites which go into detail about the intricacies of Ruby multithreading / multiprocessing?
I tried using ruby threading and basically in deadlock-free code on 1.9vm it ran into deadlocks in jruby. Yes I realize the differences are drastic (jruby has no GIL) but I wanted to know if there are strategies or set of classes for multithreaded programming in ruby that I just need to read up on.
Side note: was kinda weird going from java to ruby having to define if i want a re-enterent lock vs not.
If you use Ruby 1.9 you can try Fiber it's a big improvement in threading in Ruby
http://ruby-doc.org/core-1.9/classes/Fiber.html
http://www.infoq.com/news/2007/08/ruby-1-9-fibers
Surprisingly, the dRuby book has a chapter about DRb multithreading, and it touches some basic aspects of Ruby Multithreading. It was written by the same man who wrote dRuby/ERB, and looks pretty good.
SAP announced Blue Ruby, a version of Ruby that runs inside the ABAP Virtual Machine.
This seems to lend additional credibility to the Ruby language but, except for SAP developers, does this have any applicability to the rest of the Ruby community?
I'm just wondering what other significance this may have. Additional job opportunities, perhaps, for Ruby developers to be hired to work on SAP projects?
Any other potential benefits for Ruby programmers?
Also, something I'm not clear about: Besides MRI and JRuby, how many different implementations are there and why do I, as a Ruby programmer, need any implementation except the MRI? I understand I might need JRuby if I want to integrate with Java libraries. Are there any other times I might need to look into an implementation besides the MRI or JRuby?
I notice that Blue Ruby is compiled. Is that a big benefit and would this be the first compiled version of Ruby?
Sorry - maybe too many questions but this is being discussed as a big deal except I'm not sure why/if it really is. Would be grateful to get some feedback from people who understand Ruby (and I.T.) better than I do.
There are actually quite a few alternative implementations. The reason for so many versions is partly because while Ruby itself has a lot of fans, MRI is often considered to be not quite as nice as the language it hosts.
This is a list of all the other Ruby implementations I know of:
MRI
JRuby for Java. Its speed advantage isn't as great now that Ruby 1.9 is out, but it's still a big player for its integration with Java.
IronRuby (still in development) for .NET
MacRuby for making native Mac OS X applications. It's currently based on Ruby 1.9, but they're going to release a new LLVM-based virtual machine for the next version, which looks to offer a major speed boost and will hopefully be portable to other LLVM target platforms.
MagLev (still very much in development) for high-capacity Web apps. It will probably be a commercial product.
Rubinius is a ground-up reimplementation meant as an alternative to MRI with a much cleaner foundation.
I doubt Blue Ruby will have much of an impact on the general software development landscape. It will probably be nice for SAP programmers and allow them to cast a wider net for potential hires since Ruby is somewhat more popular than ABAP.
All of the current Ruby implementations are compiled to bytecode. Contrary to SAP's claims, as of Ruby 1.9, MRI itself includes a bytecode compiler, though the ability to save the compiled bytecode to disk disappeared somewhere in the process of merging the YARV virtual machine. JRuby is compiled into Java .class files. I don't have a lot of details on MagLev, but it seems safe to say it will take that road as well.
Each implementation has its own use cases. JRuby is useful for much the same reasons Jython is. IronRuby will be useful in a .NET environment, when it exists in a usable state.
Things like this make Ruby more acceptable on the Enterprise level, and hasten the spread of Good Programming Languages.
Of course, Blue Ruby is intended for SAP related people. I don't think is going to have much more of an impact on the Ruby community because most Ruby developers are not related to ABAP development.
The main purpose of Blue Ruby is to bring a powerful Scripting Language into the ABAP world, providing more tools for ABAP developers.
You can read my blog on Blue Ruby providing an SE16 (Data table explorer) emulator.
https://weblogs.sdn.sap.com/pub/wlg/14222
Greetings,
Alvaro "Blag" Tejada Galindo.
Senior ABAP Consultant - SAP Mentor.
What are the advantages/disadvantages of the major Ruby VMs (things like features, compatibility, performance, and quirks?) I know there are also some bonus features like being able to use Java interfaces through JRuby, too. Those would also be helpful to note. Does any VM have a clear advantage at this point, and in what contexts?
I've used both Matz's Ruby and JRuby, and they solve different tasks. If you are developing a straight Ruby or Rails app, then that will probably suffice, but if there are some powerful Java libraries that would help a lot, then JRuby might be worthwhile.
I haven't done anything overly complicated, but JRuby seemed to match up pretty well, at least as far as implementing the core language features (I haven't run into any differences yet, but they may exist).
One little anecdote I wish to share... I was writing a script to interact with a DB2 database. The DB2 support in Ruby is abysmal... you have to install the whole DB2 express version just to be able to compile the Ruby drivers, which didn't even work for me. I got fed up and switched to JRuby, using JDBC and a few small DB2 JDBC jars. It resolved my problem perfectly. The point? Well, if gaining access to some Java libraries will simplify the problem at hand, by all means go for it!
I hope this was helpful! Sorry I don't have any experience with other VMs....
One more caveat I have read about, but I don't know the details too well... JRuby I think supports threading via Java threads, instead of the "green" threads supported in Matz's implementation... so if you want multithreading on multicore systems, JRuby will probably serve you better... unless you want to do the threading in C.
Here's a bit of info I scrounged up on the main VMs: Ruby MRI, Ruby 1.9 (YARV), JRuby, XRuby, Rubinius, and IronRuby
There was a performance benchmark last year that compared the major VMs, but with how quickly VM development has been it probably is not as relevant today. Ruby 1.9 was generally the fastest, and still has the edge over JRuby for now, I believe.
Four VMs are currently capable of running Ruby on Rails: Ruby MRI, Ruby 1.9, JRuby, and Rubinius.
XRuby runs on the JVM, as does JRuby, and compiles the Ruby source files to a Java .class.
IronRuby runs on .NET, making use of their DLR, and allows you to integrate Ruby with the .NET libraries and infrastructure. It cannot yet run Ruby on Rails.
There is also a VM called HotRuby that lets you run Ruby source code in the browser or in Flash.
There are multiple Ruby implementations in the works right now. Which are you looking forward to and why? Do you actively use a non-MRI implementation in production?
Some of the options include:
Ruby MRI (original 1.8 branch)
YARV (official 1.9)
JRuby
Rubinius
IronRuby - Ironruby.net
MagLev (Thanks Julian) Github link
MacRuby (Thanks Damien Pollet)
Maglev. It will have the speed benefit of all the optimization that has gone into a major Smalltalk VM over many, many year. Plus it will automatically persist all your data pretty much automatically so there is no more need to monkey around with Object-Relational mapping layers and so on.
Ruby 1.9 (YARV) gives us a good idea as to where ruby is headed, but I wouldn't recommend using it for production use. While it's certainly much faster than 1.8, even some parts of the syntax keep changing, so I don't think you could call it stable. It does have some interesting new features and syntax which will surely find their way into all the other implementations over time.
JRuby and IronRuby are useful in that they give ruby access to a whole range of new libraries and environments where ruby couldn't be used otherwise. I've not found much use for them myself yet, but think it's great that they exist. They may allow ruby to infiltrate corporate environments where it wouldn't otherwise be permitted. That can only be a good thing.
Rubinius and Maglev are probably the most interesting projects, but also those where their benefit to the community is likely to be furthest into the future. Rubinius may well develop into a cutting edge 'pure' VM for the ruby language, allowing ruby code to run much faster than it can now. Maglev too seems extremely promising, backed as it is by 20+ years of VM experience. It will also provide features over and beyond a standard VM, but of course these will come at the cost of code portability.
Overall though, what I'm most excited about is the competition between these implementations. Having competing projects all working to make ruby better can only make the ruby ecosystem stronger. From what I've seen too, while the competition exists it is friendly; each project giving and taking ideas from each other. The work done by the JRuby and Rubinius teams in creating a ruby spec is probably the most important outcome so far, as it will help ensure that all implementations remain compatible.
jRuby is stable and reliable today. Maglev is very promising.
No one mentioned MacRuby yet? I guess it's a bit Mac-specific now, but it could probably be made to compile to the GNU or Étoilé objective-c runtimes too.
Also, I'm waiting for Maglev :)
What about Enterprise Ruby? This has been out there for a while.
https://www.phusionpassenger.com/enterprise