DLL callback to ruby

Dan Rathbun

@unknownuser said:

That way the C code can be compiled on both platforms as a .so file. (Windows users won't need to use Win32API calls.)

So than, how do you call a function in the dll if you don't use Win32API calls?

You expose them to Ruby (which itself is written in C,) by using the C-side functions:
rb_define_method, rb_define_module_function, & rb_define_singleton_method

I showed you an example of creating a C-side function c_add_two( anInt ), that is exposed to Ruby as the module method Alien.add_two( intarg )

You can actually write your entire Ruby module in C.

Again, I suggest you take the time to read the "Extending Ruby" from "Programming Ruby: The Pragmatic Programmer's Guide" (aka the "Pick-Axe" book.) The link is #3 in the 2nd post of this thread.

I don't have anything to say about writing Ruby extensions in any code except C/C++, other than to say "good luck" and you may wish to look at SWIG. (Links on the [Info] posting, #1 above, in second post.)

Alienizer

oh ok, I get it. So in my loader, I can simply have it load the dll which will do all of what the rb does, and remove the rb alltogether?

I am reading up on your links, much to read and learn!

Dan Rathbun

@alienizer said:

I have a testloader.rb in the plugins directory that is...

$;.push Sketchup.find_support_file("Plugins/test/")
> Sketchup;;require 'test'

...and then my test.rb loads, and in turn, the alien.dll loads as well!

Does the dll load because I have $testproc = Win32API.new("alien.dll", "test", [, "V")] in the rb script?

Yes, it is loaded by the Ruby Win32API class (which is written in C,) which calls the Windows API C function LoadLibrary. But this is Win32 platform specific, and the functions to be called must have been exported.

@alienizer said:

I do not have a require("alien.dll") in the rb script, do I still need to put it in?

Depends.. yes if you want to write extensions that expose the C-side functions, as Ruby methods; and if you plan to have your extensions be cross-platform (also compiled on Mac Xcode with as few changes as possible.)

Dan Rathbun

@alienizer said:

oh ok, I get it. So in my loader, I can simply have it load the dll which will do all of what the rb does, and remove the rb alltogether?

Well.. yes. That's what all the Ruby extended libraries do. They are compiled .so (shared object) files that create the Ruby classes and all their methods, that Ruby scripters use.

However.. the loader is actually the require() method, and the library is loaded on demand when it's needed.

Alienizer

I see. So if I use require "test.so" in my loader, then I bypass win32api and it can be cross-platform? Can the dll do everything the rb can do? How do you get the Sketchup:: object in the dll? I suppose I need sketchup.h or something?

Dan Rathbun

@alienizer said:

I see. So if I use require "test.so" in my loader, then I bypass win32api and it can be cross-platform?

Yes.. because an edition of Ruby is compiled for the platform it will run on (or even compiled on the user's platform itself.)
There is a standard platform subdir, beneath the Ruby lib dir, whose name is equal to the Ruby constant RUBY_PLATFORM.
On each platform, the Ruby require() method's C-side code, will use a platform specific API call to load shared library files (.so,.o,.dll,.dylib,...)
So on Windows, require() is likely to be calling LoadLibrary from the kernel32.dll library. On another platform such as OSX, the name of the Lib file, and the load function may differ, but in the Ruby C source, conditional defines will take care of all that.

So your code would also need to be compiled on both platforms. I don't have a Mac, but I imagine a few tweaks may be necessary, such as conditional defines, etc.

@alienizer said:

Can the dll do everything the rb can do?

I would expect so. You must realize the Ruby is written in C, and creates C objects.
A Ruby script is just an invention for human readability and productivity.
The Ruby interpreter DLL (msvcrt-ruby18.dll) reads and converts the script-type definition blocks (for modules, classes and methods,) into C calls using the functions that begin with "rb_"

@alienizer said:

How do you get the Sketchup:: object in the dll? I suppose I need sketchup.h or something?

The Sketchup object is a Ruby module, and you can call any of it's module methods from the C-side using rb_eval_string

//C
  int_ver_major = NUM2INT( rb_eval_string("Sketchup.version.to_i") );

However if you wish to use rb_funcall, you create a C-side identifier for it at the top of your code, and then in the Init_dllname function, you "init" it using rb_define_module("Sketchup"), like so:

//C

VALUE modSketchup;

// Entry point for Ruby require() method;
void Init_ExactcaseFilenameofDLL()
{
  modSketchup = rb_define_module("Sketchup");
}

Since the module already exists, it's not re-created, your just making a handle to it. (The Sketchup Ruby API objects are created in a similar way, but are part of the sketchup.exe. When Sketchup loads, the last 3 things it does is, load the Ruby interpreter DLL, define the Ruby API objects, and process the Plugins & Tools folders.)

Alienizer

aaaaaaaaaaah OK, now it's clear to me. I can see exactly what you mean and how this works.

Dan, thank you so much for your time to explain all this to me. I don't know how to thank you enough, and I wish I could return the favor, but you are obviously way above me that there is nothing you can learn from me. I realy appreciate it Dan.

Now I'm gonna go play.........

Alienizer

Dan, one last question, can the dll be compiled in 64bit or does it have to be 32bit like SK?

Does the handle return by rb_define_module('Sketchup') correspond to the ISkpApplication interface?

Dan Rathbun

@alienizer said:

Dan, one last question, can the dll be compiled in 64bit or does it have to be 32bit like SK?

I would say 32bit, because the Ruby that Sketchup loads is also 32bit. There is a 64bit Ruby edition, but it may be in the 1.9.x branch, which Sketchup cannot load even 1.9.x 32bit.

@alienizer said:

Does the handle return by rb_define_module('Sketchup') correspond to the ISkpApplication interface?

I would say "not exactly". There may be some C++ methods from that interface, that are "Ruby wrapped" into the Sketchup module, as well as others from different C++ objects.

Getting a handle on the application object (and from there it's window object, and then it's UI element objects, and so on...) are methods that the current Ruby Sketchup module lacks. You'll have to use a C++ call, as shown in the SDK examples to get the app handle.

Alienizer

Thank Dan. So far, everything works great, I even got this to work...

modUI = rb_define_module('UI');
menu = rb_funcall(modUI, rb_intern('menu'), 0, nil);

but I'm stuck on this one...

rb_funcall(menu, rb_intern('add_item'), 1, rb_str_new2('File/Testing'));

It tells me "tried to create Proc object without a block"

Where do you learn all this? I can't find any docs on rb_intern or what to pass to it. I only guess!

Dan Rathbun

The API add_item method takes 2 args, a String and a Block, ... not 1 arg.

Alienizer

@dan rathbun said:

The API add_item method takes 2 args, a String and a Block, ... not 1 arg.

Indeed! I figured it out, and the rb_intern('menu') takes one, a str of the submenu name, like "Plugins" right?

When I do rb_intern('add_submenu') with 1 arg of str "Testing", it adds only "T" to the Pluigns menu, the first letter only!?

If I don't use rb_str_new2 SK crash, Am I doing it right?

For the Block, do I have to use rb_something to pass the Block, or just the reference pointer?

Sorry to be a pain in the......

Dan Rathbun

@alienizer said:

I can't find any docs on rb_intern or what to pass to it.

At the bottom of the "Extending Ruby" chapter, of the "Pick-Axe" book:
@unknownuser said:

*ID rb_intern(char name")

Returns an ID for a given name. If the name does not exist, a symbol table entry will be created for it.

I just pasted an example that used the rb_intern to create an ID... not sure if it's really needed. You can try just passing a normal string, as the method name argument.
(Using rb_intern on the C-side, is the same as using a Symbol on the Ruby side, thus:
:test_item or "test_item".intern or "test_item".to_sym

What are the arguments, for ruby C-side functions, generally?

The list at the bottom of the "Extending Ruby" chapter, is not complete, AND that edition was written for Ruby circa 1.6.x (so it's out of date.)

For a definitive list, refer to to the function prototypes, in the Ruby C source folder:
%(#000000)[**.../include/ruby-*<version>*/ruby/ruby.h**]
.. so if your using Ruby ver 1.8.6, the path would be:
%(#000000)[**.../include/ruby-1.8.6/ruby/ruby.h**]

ADD: .. and other header files as well.

Dan Rathbun

Yea, you need to use rb_str_new2 to convert the Cstring to a Ruby String.

Alienizer

Thanks Dan

Alienizer

Dan, what is the Block expected in rb_funcall(menu, rb_intern('add_submenu')...

I keep getting the error "tried to create Proc object without a block" if I use 1 arg.

If I use 2 arg, I get "wrong number of arguments (2 for 1)" but even you said it needs 2!? Confusing

Dan Rathbun

@alienizer said:

For the Block, do I have to use rb_something to pass the Block, or just the reference pointer?

Not sure... the proc and block functions are listed in intern.h

Depends on if the block / proc will be defined at runtime on the Ruby side, or before hand in your C code.

This generated doxygen website is old (v 1.8.4) but you may find it easier to find things:
http://www.ruby-doc.org/doxygen/current/globals.html#index_r

Alienizer

Thanks Dan

Dan Rathbun

@alienizer said:

Thanks Dan

no problemo ...

Also, if you have the Ruby Reference CHM, when you wish to see the C-side source for a method, you can click within the method's definition area, and a source box will unfold.

Alienizer

Sweet! But only ruby18-core.chm works out of the 3! Or is it me?

I just posted http://forums.sketchucation.com/viewtopic.php?f=180&t=39119 another challange for you