Simple Extension for Mac

[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.