programming ruby 2nd--extending ruby 1

programming ruby 2nd--extending ruby 1

1.Ruby Object  in c
2.juke box extension
3.memory allocation
4.ruby type system
5.create an exception
6embed a ruby interpreter
7.bridge to other language
8.c api
1.
p269
Sometimes, though, life is more complicated. Perhaps you want to define a global variable
whose valuemust be calculated when it is accessed. You do this by defining hooked
and virtual variables. A hooked variable is a real variable that is initialized by a named
function when the corresponding Ruby variable is accessed. Virtual variables are similar
but are never stored: their value purely comes from evaluating the hook function.
See the API section that begins on page 294 for details.
If you create a Ruby object from C and store it in a C global variable without exporting
it to Ruby, you must at least tell the garbage collector about it, lest ye be reaped
inadvertently.
static VALUE obj;
// ...
obj = rb_ary_new();
rb_global_variable(obj);