Re: lua source as config file
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- Subject: Re: lua source as config file
- From: Flemming Madsen <lua@...>
- Date: 2007年2月08日 20:47:14 +0100
What i usually do is something like:
---------
function read_settings(filename)
local f=loadfile(filename)
local t={}
setfenv(f,t)
f()
return t
end
local settings=read_settings(filename)
--------
Nice.
I was trying to elaborate on this a little bit to see if I could make
sort of a mini DSL for
configuration of a syslogd replacement i am working on.
It should give me the possibility of defining a number of records with
settable defaults.
I ended up with a config file like syntax like
#config
defaults [[ rotlog = 5 ]]
config [[
name = "online.log"
programs = { "pppd", "chat" }
]]
defaults [[ level = "error" ]]
config [[
name = "fatal"
size = 200 * k
pattern = { "^[Ff]atal", "%W[Ff]atal" }
]]
config[[ ]] -- Catch all
The first shot was with table constructors as argument to "defaults" and
"config", but inspired
by this thread I thought i'd try and make the argument an ordinary lua
chunk. The experience was
a little mind boggling, trying to figure out how to keep everything in
working order along with
the required setfenv's. Anyway here is what i came up with, in case it
is of use to anyone.
-- Define the default defaults, the resulting table & the sandbox
local logconfigs = {}
local cfg = {
log_defaults = {
dir = "/var/log";
name = "messages";
action = { file=1 };
size = 100 * 1024;
rotlog = 1;
level = "info";
facilities = "*";
pattern = {};
programs = {};
shortfmt = 1;
dobreak = 0;
};
k = 1024;
m = 1024 * 1024;
--
logconfigs = logconfigs;
loadstring = loadstring;
setmetatable = setmetatable;
setfenv = setfenv;
table_insert = table.insert;
}
-- Cater for the defaults[[...]] section in the config file
function cfg.defaults(s)
conf_defaults = {k = k, m = m}
setmetatable(conf_defaults, {__index = log_defaults}) -- Route through
local chunk = loadstring(s)
setfenv(chunk, conf_defaults)
chunk()
defmeta = { __index = conf_defaults }
end
setfenv(cfg.defaults, cfg)
cfg.defaults'' -- Default is straight through to log_defaults
-- Cater for the config[[...]] sections in the config file
function cfg.config(s)
local v = {}
setmetatable(v, defmeta)
local chunk = loadstring(s)
setfenv(chunk, v)
chunk()
table_insert(logconfigs, v)
end
setfenv(cfg.config, cfg)
-- The sandboxed loader
function cfg.loadconfig(chunk)
setfenv(chunk, cfg)
chunk()
end
-- Load config file
cfg.loadconfig(assert(loadfile("/etc/syslogl.conf")))