[Ironruby-core] Setting and initializing instance variables on RubyClasses

Tomas Matousek Tomas.Matousek at microsoft.com
Mon Jul 26 11:33:44 EDT 2010


Cool! :)

Tomas

From: ironruby-core-bounces at rubyforge.org [mailto:ironruby-core-bounces at rubyforge.org] On Behalf Of Charles Strahan
Sent: Monday, July 26, 2010 5:24 AM
To: ironruby-core at rubyforge.org
Subject: Re: [Ironruby-core] Setting and initializing instance variables on RubyClasses

It's actually an entire game engine port :).

http://www.rpgmakerweb.com/product.html?prod=xp

However, I don't believe "port" is the correct word - perhaps "reimplementation" would be more accurate.  I don't have access to RPG Maker's source code, so I've written the entire game engine from the documented APIs, and by injecting little bits of Ruby into RPG Maker's Ruby runtime to fill in any of the blanks.  Finally, I ran several games through my "port" and fixed any little bugs I came across.  It was no small feat, I assure you :).

So, as you can probably imagine, the rendering is highly coupled to the rest of the engine.  As a result, I have no expectations to use it anywhere else.  Sure, I could abstract away stuff like drawing rectangles and circles to bitmaps, but anything more than that (sprites, windows, etc.) wouldn't make any sense outside of this particular game engine.  I'm sure I could do it all in Ruby (and have, when I wrote the WinForms impl) - but I don't find IronRuby as easy to debug as C# (yet). So, if I'm going to write any C# code, that C# code will need to directly interop with the rest of the Ruby modules and classes (in most cases).  I'm sure the IronRuby APIs will change from version to version, but that's not a big deal in my case.  I'm fine updating my code to match the latest release, or just tying my code to a specific version.  My current goal is to make my port run on Silverlight and, consequently, Windows Phone 7 so that people can redistribute their games on the market place or on the web; in both cases, targeting a specific version of IronRuby is easy.  If, on the otherhand, I wanted to distribute a platform agnostic implementation, then I would run into problems as there's no telling what version of IronRuby is installed on each computer.

In case you're curious about the legality of my project, I assure you that it's quite fine.  The only thing I plan to redistribute is some code that will run existing games.  No copyright protected materials such as images, audio, video etc will be redistributed - nor do I have any interest in developing the part of the RPG Maker software that actually let's you make games, which means that my project won't impact Enterbrain's profits in any way (their EULA allows the customer to redistribute their games however the customer sees fit, so they only make money when someone purchases RPG Maker to develop games).


If you're still interested in taking a peek at my code, I plan on distributing the source on GitHub some time soon.


-Charles

On Sun, Jul 25, 2010 at 1:50 PM, Tomas Matousek <Tomas.Matousek at microsoft.com<mailto:Tomas.Matousek at microsoft.com>> wrote:
So you're building a graphics library based on WritableBitmap?
You can certainly try to build Ruby classes in C# however it might be much easier and more flexible to build basic data structures and algorithms that need to be highly optimized in regular C# (no Ruby specific stuff) and then wrap them into a Ruby class in Ruby code. Your C#.dll might define a regular C# class Graphics:

namespace MyNamespace {
public class Graphics {
                public void DoStuff() { }
}
}

And then you'll write a Ruby wrapper:

require 'graphics.dll'
class MyNamespace::Graphics
  def ruby_facade
     do something ruby-ish
     do_stuff
  end
end

Maybe if you gave concrete examples of the APIs you're designing it might help me understand why this wouldn't be sufficient. The goal of IronRuby is to allow you to use interop with regular C# code easily and efficiently without a need to specialize it for Ruby. For calling back to Ruby you can use C#'s dynamic features. If there is anything that prevents you from doing so  let us know. The additional advantage of this approach is that your C# code can easily be used from other languages as well.

Re: CallSiteStorage: any time you need to dynamically call a method using Ruby semantics you should use it to do so. Three are plenty of use cases throughout the library that you can see for examples (search for Storage).

We don't have any optimizations in place for class variable access. So TryGetClassVariable always looks up a dictionary.

Tomas

From: ironruby-core-bounces at rubyforge.org<mailto:ironruby-core-bounces at rubyforge.org> [mailto:ironruby-core-bounces at rubyforge.org<mailto:ironruby-core-bounces at rubyforge.org>] On Behalf Of Charles Strahan
Sent: Sunday, July 25, 2010 3:02 AM

To: ironruby-core at rubyforge.org<mailto:ironruby-core at rubyforge.org>
Subject: Re: [Ironruby-core] Setting and initializing instance variables on RubyClasses

By native Ruby library/extension I meant an implementation in C.

D'oh!  I realized that's what you'd meant after I replied.  Woops :).
If you absolutely need to implement your Ruby classes in C# (I would be interested to understand why)

I probably don't need to for the most part, but I do have some motivation for doing so.  Performance is a must.  Also, I'm doing a lot of WritableBitmap manipulations, using (among other things) the WritableBitmapEx on CodePlex, which feels a lot more natural in C#.  I've already completed my little project using pure [Iron]Ruby and WinForms, but I figured I'd try out the IronRuby API & C# now that I'm porting it to Silverlight.  The interop with plain vanilla C# libs is great, but I can't picture pulling off stuff like #_dump and ._load without going the API route.  Also, I think it'll be good practice using the IronRuby API from C#, as I'd like to contribute back to libraries (ruby-debug-ide and ffi are at the top of my list).
To allocate data bound to a runtime we provide GetOrCreateLibraryData method on RubyContext.

I'll have to check that out.  For now, using the following pattern seems to work well enough:

  // from the Graphics class
  self.TryGetClassVariable("renderables", out renderables)  // where self is the RubyClass

  // from another class:
  var graphicsClass = context.GetClass(typeof(Graphics));
  graphicsClass.TryGetClassVariable("renderables", out renderables)


I also (think) I saw some code throughout IronRuby that used CallSiteStorage to interact with ruby objects.  Would that yield better performance?


Cheers,

-Charles
On Wed, Jul 7, 2010 at 11:15 AM, Tomas Matousek <Tomas.Matousek at microsoft.com<mailto:Tomas.Matousek at microsoft.com>> wrote:
By native Ruby library/extension I meant an implementation in C.

Although possible it's not easy to simulate Ruby classes definition in C# in a declarative way. I would suggest writing your implementation in Ruby and calling .NET when you need so using IronRuby's .NET interop.
If you absolutely need to implement your Ruby classes in C# (I would be interested to understand why) you can use C# instance fields instead of Ruby's instance variables. They won't be exposed as instance variables to Ruby but they would be faster to work with. The fact they are not exposed shouldn't matter since instance variables should be a private implementation detail of the class anyways.

It is more complicated with per-class data. You shouldn't use static fields since the value should be bound to Ruby runtime. To allocate data bound to a runtime we provide GetOrCreateLibraryData method on RubyContext. You'll find a few places where it's used in IronRuby.Library. But before you dig into that consider writing your code in Ruby and perhaps parts of it that are perf critical in pure C# (w/o Ruby specific attributes). Our C# interop is strong so there shouldn't be generally a need for writing Ruby code in C#.

Tomas

-----Original Message-----
From: ironruby-core-bounces at rubyforge.org<mailto:ironruby-core-bounces at rubyforge.org> [mailto:ironruby-core-bounces at rubyforge.org<mailto:ironruby-core-bounces at rubyforge.org>] On Behalf Of Charles Strahan
Sent: Monday, July 05, 2010 11:55 PM
To: ironruby-core at rubyforge.org<mailto:ironruby-core at rubyforge.org>
Subject: Re: [Ironruby-core] Setting and initializing instance variables on RubyClasses

Wow, that was quick!  Thanks Tomas.


If by Ruby native you mean mostly implemented in Ruby, then no.

I mentioned the Ruby snippets just for clarification.  If I understand correctly, SetClassVariable has the same semantics as declaring what Ruby would call a class variable, as in @@some_var.  @@some_var would be visible to the whole class hierarchy, so `FancyGraphics < Graphics; end` would share the same @@some_var instance - which is _not_ what I'd like.

Just curious how that might work using the IR APIs.


I assume the second question made sense. If not, let me know.


Cheers,

Charles

-----Original Message-----
From: ironruby-core-bounces at rubyforge.org<mailto:ironruby-core-bounces at rubyforge.org>
[mailto:ironruby-core-bounces at rubyforge.org<mailto:ironruby-core-bounces at rubyforge.org>] On Behalf Of Tomas Matousek
Sent: Tuesday, July 06, 2010 1:17 AM
To: ironruby-core at rubyforge.org<mailto:ironruby-core at rubyforge.org>
Subject: Re: [Ironruby-core] Setting and initializing instance variables on RubyClasses

What is your overall goal? Are you implementing a Ruby native library?

Tomas

-----Original Message-----
From: ironruby-core-bounces at rubyforge.org<mailto:ironruby-core-bounces at rubyforge.org>
[mailto:ironruby-core-bounces at rubyforge.org<mailto:ironruby-core-bounces at rubyforge.org>] On Behalf Of Charles Strahan
Sent: Monday, July 05, 2010 10:59 PM
To: ironruby-core at rubyforge.org<mailto:ironruby-core at rubyforge.org>
Subject: [Ironruby-core] Setting and initializing instance variables on RubyClasses

Hello,

How can I go about setting an instance variable on a RubyClass?

Here's some code for context:

   [RubyClass("Graphics")]
   public class Graphics
   {
       [RubyMethod("frame_rate", RubyMethodAttributes.PublicSingleton)]
       public static int GetFrameRate(RubyClass self)
       {
           // What goes here?
           // I could use self.TryGetClassVariable, but that's a *class* variable, correct?
           // I want to achieve the same thing as "return @frame_rate",
           // not "return @@frame_rate"
       }

       [RubyMethod("frame_rate=", RubyMethodAttributes.PublicSingleton)]
       public static void SetFrameRate(RubyClass self, int frameRate)
       {
           // Same thing here. I could do this:
           // self.SetClassVariable("frame_rate", frameRate);
           // but I want to achieve the same as this:
           // @frame_rate = frame_rate
       }
   }


Another option *just* dawned on me; how about these two:
self.Context.SetInstanceVariable(self, "frame_rate", frameRate); self.Context.TryGetInstanceVariable(self, "frame_rate", out frameRate);

Is that what I'm looking for?


One more question:  is there a way to get the library initializer to invoke a callback so that I may perform some initialization for the RubyClass itself?  In the case above, I'd like to initialize the frame_rate when the RubyClass is created.  As an example:

class Graphics
 attr_accessor :frame_rate
 frame_rate = 40
end
...
Graphics.frame_rate = something_else


I'd like that "frame_rate = 40" to happen when the assembly is loaded by the IronRuby runtime, if possible.  I'm sure I could type that into my auto-generated LibraryInitializer, but I'd rather do this declaratively, perhaps using Attributes (like RubyMethod and RubyClass, etc).


Thanks,
-Charles

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