From: Charles Thornton <ceo@...>
Date: 2007-12-14T19:16:35+09:00
Subject: IRHG - PUSH_FRAME?

The following define statement is driving me crazy
I have never seen a  #define used this way!

Can someone explain what is going on here?

Does this somehow create a new frame without
allocation, and add it to a ruby_frame linked list?

#define PUSH_FRAME() do {        \
    struct FRAME _frame;        \
    _frame.prev = ruby_frame;        \
    _frame.tmp  = 0;            \
    _frame.node = ruby_current_node;    \
    _frame.iter = ruby_iter->iter;    \
    _frame.argc = 0;            \
    _frame.flags = 0;            \
    _frame.uniq = frame_unique++;    \
    ruby_frame = &_frame

#define POP_FRAME()              \
    ruby_current_node = _frame.node;    \
    ruby_frame = _frame.prev;        \
} while (0)