Re: is setfenv useless?
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- Subject: Re: is setfenv useless?
- From: "mr. Aleph" <mraleph@...>
- Date: 2006年3月06日 13:46:54 +0600
PA wrote:
> function: 0x10ff60
> my very own require "table"
> table: 0x101b60 <<<< LOOK HERE (mark added by mr. Aleph)
> function: 0x1127d0
> my very own require "table"
> table: 0x101b60 <<<< LOOK HERE (mark added by mr. Aleph)
This output only shows that require still uses the same old environment.
If you try the attached program, you'll get the following output:
>a env is old
>testf env is old
>b env is old
>a env is new
>testf env is old
>b env is old
>a env is old
>testf env is old
>b env is old
>a env is new
>testf env is old
>b env is old
Which shows that "callee does not inherit the environment of the caller".
PS Also your trick must be upgraded to deal with upvalues. But this is
really easy to do with the help of debug.* facilities.
PPS And... Thank you. You've shown me some interesting tricks, I've
never thought of...
require "testf"
local function clone(f)
return loadstring( string.dump( f ) )
end
old = true
function b()
print("b env is", old and "old" or "new")
end
function a()
print("a env is", old and "old" or "new")
print("testf env is", testf "old" and "old" or "new")
b()
end
a()
local newenv = {}
newenv.testf = testf
newenv.print = print
newenv.b = b
setfenv(a, newenv)
a()
local aClone = clone(a)
aClone()
setfenv(aClone, newenv)
aClone()
#include "lua.h"
#include "lauxlib.h"
#include "lualib.h"
int ltest(lua_State *L) {
lua_getglobal(L, luaL_checkstring(L, 1));
return 1;
}
int luaopen_testf (lua_State *L) {
lua_pushcfunction(L, ltest);
lua_setglobal(L, "testf");
return 1;
}