C:\Users\Giacomo>python --version
Python 2.7.6

C:\Users\Giacomo>gem install therubyracer
Temporarily enhancing PATH to include DevKit...
Building native extensions.  This could take a while...
ERROR:  Error installing therubyracer:
        ERROR: Failed to build gem native extension.

    D:/Programmi/Ruby200-x64/bin/ruby.exe extconf.rb
creating Makefile
Impossibile trovare il percorso specificato.
Impossibile trovare il percorso specificato.
Impossibile trovare il percorso specificato.
D:/Programmi/Ruby200-x64/lib/ruby/gems/2.0.0/gems/libv8-3.16.14.3/ext/libv8/buil
der.rb:58:in `setup_python!': libv8 requires python 2 to be installed in order t
o build, but it is currently not available (RuntimeError)
        from D:/Programmi/Ruby200-x64/lib/ruby/gems/2.0.0/gems/libv8-3.16.14.3/e
xt/libv8/builder.rb:42:in `block in build_libv8!'
        from D:/Programmi/Ruby200-x64/lib/ruby/gems/2.0.0/gems/libv8-3.16.14.3/e
xt/libv8/builder.rb:40:in `chdir'
        from D:/Programmi/Ruby200-x64/lib/ruby/gems/2.0.0/gems/libv8-3.16.14.3/e
xt/libv8/builder.rb:40:in `build_libv8!'
        from D:/Programmi/Ruby200-x64/lib/ruby/gems/2.0.0/gems/libv8-3.16.14.3/e
xt/libv8/location.rb:24:in `install!'
        from extconf.rb:7:in `<main>'


Gem files will remain installed in D:/Programmi/Ruby200-x64/lib/ruby/gems/2.0.0/
gems/libv8-3.16.14.3 for inspection.
Results logged to D:/Programmi/Ruby200-x64/lib/ruby/gems/2.0.0/gems/libv8-3.16.1
4.3/ext/libv8/gem_make.out

C:\Users\Giacomo>