1*572c4311Sfengbojiang-- make global variables readonly 2*572c4311Sfengbojiang 3*572c4311Sfengbojianglocal f=function (t,i) error("cannot redefine global variable `"..i.."'",2) end 4*572c4311Sfengbojianglocal g={} 5*572c4311Sfengbojianglocal G=getfenv() 6*572c4311Sfengbojiangsetmetatable(g,{__index=G,__newindex=f}) 7*572c4311Sfengbojiangsetfenv(1,g) 8*572c4311Sfengbojiang 9*572c4311Sfengbojiang-- an example 10*572c4311Sfengbojiangrawset(g,"x",3) 11*572c4311Sfengbojiangx=2 12*572c4311Sfengbojiangy=1 -- cannot redefine `y' 13