2008 February 1st Friday (二月 一日 金曜日）

Blizzard came again.  Many people whoes home is not in Wuxi began to worry about how to go back their home.
I have look through the compilers principle and tools again.  The past difficulties is easy for me to understand.
In Pascal lanuage, a procedure or a function can be embeded into another.  At run-time, the inner procedure or
function can access the variables, functions or procedures defined in its outer.  To accelerate that control link
accesses, display table technique usualy was adopted.  The every entry in display table represented a embedding
layer.  When a function or procedure was invoked, the program can enter a new layer, and a new active record was
created, or the program still stay the original layer and just build a new active record for invoking procedure,
push it into the run-time stack.