How to update GR.rb

1. Start when a new version of sciapp/gr is released.

2. Send pull request to update homebrew libgr package.

3. Update red-data-tools package if possible.

4. Review file changes in sciapp/gr, GR.jl, python-gr

5. Update ffi.rb

6. Update gr.rb and gr3.rb.

Ruby's Integer and Float are automatically converted to C types: int, float, and double. You do not need to convert the String too. This is a feature provided by Fiddle. But, be careful if you want to pass an array or a pointer as an argument.

Arrays are converted to the default type. If the argument type is not the default type, you must convert it manually. You can use GRCommonUtils methods such as int, float, double, and uint for this purpose.

A convenient inquiry methods are provided for passing a pointer as an argument. But keep in mind that this is not always perfect. If you need a "pointer of pointers", you have to do it yourself.

7. Write some tests if possible.

8. Leave for a few days.

9. Update the Gem.