Re: lua_getinfo(L,"n",&ar) doesn't use upvals to guess function name?
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- Subject: Re: lua_getinfo(L,"n",&ar) doesn't use upvals to guess function name?
- From: RLake@...
- Date: 2004年3月18日 12:58:24 -0500
> local function bar()
> return foo() -- can call "foo", because foo is an upvalue
here
> end
> My workaround for this will be to query the calling 'ar' myself and
> search the named upvals (if getinfo fails to find the name through the
> normal mechanism). Is there any reason why this is a bad idea?
In this particular case, I don't think it will work. return foo() is
a tailcall, so the stack frame for bar no longer exists when/if foo
blows up.
I am strongly of the opinion that if you think objects should have
names, you should name them explicitly. Lua provides some support for
this, although I admit that it may not be sufficient for what you might
want to be doing. The code I use (from memory, my Lua stuff is at home)
looks like this:
-- module naming
local names = {setmetatable({}, {__mode = "k"})
function Named(name)
return function(val)
if val then names[val] = name end
return val
end
end
function Register(name)
return function(table)
for k, v in table do
if type(v) == ¨"function" and type(k) == "string" then
Named(name..k, v)
end
end
return Named(name, table)
end
end
function nameOfFunc(level)
local info = debug.getinfo(level, "f")
if info and info.func then return names[info.func] end
-- more stuff to deal with the self parameter
end
--
Using this, unfortunately, requires changing:
local function foo() ... end
to
local foo; foo = Named "foo" (function() ... end)
I would find this easier to live with if it were not for the close
parenthesis; the
rest of it is a simple preprocessor substitution. It works nicely with
tables,
though:
-- style 1:
local meta = Register "fancyMetaTable" {
__index = function(t, k) ... end
__add = function(t, a, b) ... end
}
-- style 2:
local meta = {}
function meta:__index(k) ... end
function meta:__add(k) ... end
Register "fancyMetaTable" (meta)
HTH
Rici