$compile_id
編譯id變量
Persistant compile identifier. As an alternative to passing the same
compile_id to each and every function call, you can set this compile_id
and it will be used implicitly thereafter.
永久的編譯鑒別號.作為一個可選辦法將相同的編譯號傳遞給每個函數(shù)調用,你可以設置這個編譯id,隨后此id將會被隱含地使用.