Hi Liming, On Dec 18, 2007 6:35 PM, lianliming <lianliming / gmail.com> wrote: > Hi all, > > I am hacking some existing Ruby c extension, and found code like > following: > > #ifdef RUBY_VM > ..... > #endif This will be code in ruby-oci8 trunk. There is no article documenting RUBY_VM. I use it to check whether the ruby's thread model is green or native, in other words, whether the ruby version is 1.8 or 1.9. #ifdef RUBY_VM code for ruby 1.9 #else code for ruby 1.8 #endif I want RUBY_VERSION_MAJOR, RUBY_VERSION_MINOR and so on. But there is no macro describing ruby version. I use RUBY_VM instead.