Hi!
I have a problem while trying to use a to-be-closed variable as usual upvalue.
An upvalue's lifespan might go beyond the current block, and the lifespan is unknown at compile time.
This is a code of simple Lua program to explain the problem:
local say = print
local function log_start_time()
local logfile <close> = assert(io.open("log.txt", "a"))
local function write_to_log(msg)
logfile:write(msg.."\n")
end
write_to_log("Started at "..os.date())
-- Usually, only start time is written to the log
-- Unless user specified "--log-everything" option
if arg[1] == "--log-everything" then
-- All messages to say() must go also to the log
function say(msg)
print(msg)
write_to_log(msg)
end
-- Now I want the file to remain opened after exiting from the current function
-- I need to de-<close>-ify the variable "logfile"
-- How can I do that?
end
end
log_start_time()
say("Hello")
say("Result = "..some_long_time_calculations())
say("Bye")
