Simple Extension for Mac

thomthom

Had a look at it myself. Looks like a Ruby C Extension wrapped in C++ with extra stuff I expect if for the exporter.

Al: The Ruby C Extension sample I linked to is a bare bone example of connecting Ruby and C. Now, it is possible to write these extensions in C++, I've seen examples - they had to extern the C++ functions as C type functions.

That SimpleExtension sample didn't seem that simple to me, certainly more than the minimum of what is needed. Look at how people in the Ruby community is developing Ruby C Extensions with C++ and you will find simpler examples.

thomthom

StackOverflow got several threads on it:
http://stackoverflow.com/questions/10167149/compiling-ruby-c-extension
http://stackoverflow.com/a/2060716/486990

Noel Warren have used Rice:
http://rice.rubyforge.org/

And just found this which was interesting in regard to raising exceptions:
http://old.thoughtsincomputation.com/posts/ruby-c-extensions-c-and-weird-crashing-on-rb_raise

olilej

I looked over that SimpleExtension example, it seems very promising.

By the way, what exactly are the real benefit of using Ruby C Extension ? Does this have to do with performance ? As in SketchUp 2013, C++ SDK doesn't allow model interaction, it would be very interesting if we could improve the plugins efficiency with that possibility.

Olivier

thomthom

I use C Extensions when I need to do many calculations. Vertex Tools became 200+ times faster in calculating the soft selection when I ported the code to C Extension.

Just calling Ruby functions won't be faster. You'd have to be doing calculations and other processing for it to be faster.

It's not just performance though, you might want to spawn off other processes. Use C libraries.

Al Hart

We had about the same experience as ThomThom.

Calling ruby functions from C-code was slower than calling them from ruby directly in SketchUp.

e.g. The C-code replacement for:

value = model.get_attribute “dictionaryname”, key, defaultvalue)

can be done directly, (actually rather indirectly), from C-code, but the execution time is slower than in SketchUp ruby.

But other things, such as maintaining a table for vertices, and then doing special processing for vertices was faster.

Also, we were able to use Windows dialogs, functions in other Windows DLLS, etc. and attach them to SketchUp.

Also, we were able to use all the Ruby stuff from C++ because ruby\1.8\i386-mswin32\ruby.h, (part of the ruby code), includes

#if defined(__cplusplus)
extern "C" {
#endif

Back to the original question.

Has anyone interfaced to C routines from the Mac, and if so could you share a sample of some sort to get us started...

thomthom

@al hart said:

Has anyone interfaced to C routines from the Mac, and if so could you share a sample of some sort to get us started...

https://bitbucket.org/thomthom/sketchup-ruby-c-extension

Al Hart

@thomthom said:

https://bitbucket.org/thomthom/sketchup-ruby-c-extension

Thanks, ThomThom, that looks like what I am looking for.

I see you had posted it before, but I didn't know what it was at the time.

thomthom

Mind you, I recently found http://rubyinstaller.org/downloads/ which I think is a better choice for Windows than the Visual Studio solution I'd used.

olilej

I've been playing around with C Extension recently and I would like to know how if there is an equivalent of is_a? ruby function in C level.

I found rb_obj_is_instance_of but it seems to be only meant for native ruby types.

Al Hart

[Ignore this for a minute - I need to add a second parameter for what the value to pass to is_a?]

You can execute the equivalent of any ruby function using rb_intern() and rb_funcall()

Try this:


VALUE fid = rb_intern("is_a?");
VALUE vret = rb_funcall(klass, fid, 0);

Al Hart

Here is a better example, equivalent to

Sketchup.is_a?(Module)



VALUE Sketchup = rb_path2class("Sketchup");
VALUE Module= rb_intern("Module");
VALUE is_a = rb_intern("is_a?");
VALUE result = rb_funcall(Sketchup, is_a, Module, 0);

Dan Rathbun

@olilej said:

I've been playing around with C Extension recently and I would like to know how if there is an equivalent of is_a? ruby function in C level.

If you have the CHM... you can click on the method description, and the C source will popup:
(Also works for online version, but the source link must be clicked directly, and is only visible when the mouse is hovering over the method description.)

Dan Rathbun

So it looks like there are some macros defined in C, to make life easier ... CLASS_OF(), RCLASS_SUPER(), etc.

Dan Rathbun

Pragmatic Programmer: Extending Ruby 1.9

olilej

Great, my goal is to make sure I'm dealing with a Entity in order to access its attributes.

Here is the code I've come up with.

VALUE result = rb_obj_is_kind_of(obj, rb_path2class("Sketchup;;Entity"));
if (Qtrue == result){
	VALUE rval = rb_funcall(obj, rb_intern("get_attribute"), 2, rb_str_new2("dynamic_attributes"), rb_str_new2("..."));
	...
}

Dan Rathbun

Only Sketchup::ComponentDefinition and Sketchup::ComponentInstance will have dictionaries with that special name.