debug.getupvalue
Summary
Returns the name and value of an upvalue
Prototype
name, value = debug.getupvalue (level, upvalue)Description
Similar to debug.getlocal, returns the names and values of the upvalues for the nominated function. See also debug.setupvalue.
function newCounter ()
local n = 0
return function () -- anonymous function
n = n + 1
return n
end -- function
end -- newCounter
c = newCounter ()
c () -- count a couple of times
c ()
-- show upvalues in c
local i = 1
repeat
name, val = debug.getupvalue (c, i)
if name then
print ("index", i, name, "=", val)
i = i + 1
end -- if
until not name
-->
index 1 n = 2
In this example the function c is a closure (with associated upvalue "n").
NOTE: Lua does not let you see or change upvalues for C functions (eg. string.gfind).See Also ...
Topics
Lua base functions
Lua bc (big number) functions
Lua bit manipulation functions
Lua coroutine functions
Lua debug functions
Lua io functions
Lua math functions
Lua os functions
Lua package functions
Lua PCRE regular expression functions
Lua script extensions
Lua string functions
Lua table functions
Lua utilities
ScriptingLua functions
debug.debug (Enters interactive debugging)
debug.getfenv (Returns the environment of an object)
debug.gethook (Returns the current hook settings)
debug.getinfo (Returns a table with information about a function)
debug.getlocal (Returns name and value of a local variable)
debug.getmetatable (Returns the metatable of the given object)
debug.getregistry (Returns the registry table)
debug.setfenv (Sets the environment of an object)
debug.sethook (Sets a debug hook function)
debug.setlocal (Sets the value of the local variable)
debug.setmetatable (Sets the metatable for an object)
debug.setupvalue (Sets an upvalue for a function)
debug.traceback (Returns a string with a traceback of the stack call)(Help topic: lua=debug.getupvalue)
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