Simple Extension for Mac

[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...

404 — Bitbucket

(bitbucket.org)

[Al Hart]

@thomthom said:

404 — Bitbucket

(bitbucket.org)

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.