Simple Extension for Mac

Al Hart

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.