Joshua Wise

wiki

I've also been doing some other random stuff lately. RiciLake suggested that I start documenting stuff, so as I find interesting things that I've done, I'll post them here. Like him, I can be found on the IRC channel, which is available at irc://irc.freenode.net/#lua -- my username is usually joshua_. If you're looking for me elsewhere on the web, try http://joshuawise.com/ .

Code

• I've been working on some database bindings for Lua recently, including what I'm calling LuaOnLails?. Grab the latest from http://nyus.joshuawise.com/lails.lua . This requires RiciLake's GeneralizedPairsAndIpairs. (Lua 5.1)
  • Have a test driver: http://nyus.joshuawise.com/lails-testdriver.lua
  • Here's a quick way to show it off. This code snippet migrates data from a Lua-based datastore to a SQLite datastore. The data was originally stored in a Lua file called "objects.lua", which contained a table called "objects" that mapped from hashes to descriptions. Really, it's a lot less complex than it sounds, especially when you do it with Lails.

    require"lails"
    require"luasql.sqlite"
    env = luasql.sqlite()
    conn = env:connect("/home/joshua/mirror-objects.sqlite")
    
    db = lails.db:new(conn){
            tables = {
                    objects = {
                            primkey = "hash"
                    }
            }
    }
    test = db.objects
    
    dofile("objects.lua")
    conn:execute("BEGIN TRANSACTION;")
    for k,v in pairs(objects) do
            test[k] = {
                    moddate = v.moddate,
                    mimetype = v.mimetype,
                    mirrored = v.mirrored,
                    length = v.length,
                    lastaccessed = v.lastaccessed,
                    url = v.url
            }
    end
    conn:execute("COMMIT;")
    

    I whipped this up in about 25 minutes this afternoon. The neat bit about this is that when I convert the user of the datastore over, I won't really have to change much -- the only difference will be that I won't have to load and store the datastore, I can just act directly on the database. More on how Lails actually works later.
  • Syntax has changed recently as I introduced relational stuff to Lails -- mostly in how you initialize the database. Take a look at http://nyus.joshuawise.com/reltest.lp-txt for the new way to initialize a database, and a look at playing with relations. Other examples updated 2006-02-04 later in the day (and syntax changed a bit too). That database was created with the commands:

     sqlite> INSERT INTO users (id, username) VALUES (1, "joshua");
     sqlite> INSERT INTO users (id, username) VALUES (2, "someone");
     sqlite> INSERT INTO acls (id, resource, user) VALUES (1, "/", 1);
     sqlite> INSERT INTO acls (id, resource, user) VALUES (2, "/home/someone", 2);
     sqlite> INSERT INTO acls (id, resource, user) VALUES (3, "/tmp", 2);

    Slick, huh? Did this 2007-02-04 (early in the morning; if you saw it mid day 2007-02-04, you're already out of date)
• I wrote a polyglot.

  #define function main() { int i = 0;
  function --i; printf("Hello, world!\n"); } /*
  x() print("Hello, world!") end x() -- */
  

• Other undocumented stuff:
  • I got LuaSQL and CGILua running with FastCGI on Apache2.2 and Lua5.1. I should write up how I did that.
  • I wrote a live mirror script in Lua. Add a little bit of mod_rewrite magic, and it's fairly functional. Think Apache mod_cache, except written in Lua because I suffered from a little bit of NIH syndrome, because I didn't know about it, and because I wanted to do it in Lua to play with CGILua. http://nyus.joshuawise.com/live-mirror.lcgi-txt
• Various naim hacks
  • METAR downloader and translator that responds to requests from an IRC channel.
  • "Latest xkcd" IRC bot.
  • Utility bot with !epithet, !lart, etc support.
  • Protocol driver support for naim; oscar.pd.
• Wrote a quick hooks library to demonstrate a better way to do something than

  for k,v in pairs(files_in_directory) do
    dofile(v)
    client_command(...)
    client_command = nil
  end

  to someone on IRC. Get it from http://joshuawise.com/hooks.lua . A quick test for it is:

  require"hooks"
  myhooks = {}
  myhooks.test = hooks:new()
  myhooks.ref1 = myhooks.test:insert(function (foo, bar) print("Test 1", foo, bar) end, 100)
  myhooks.ref2 = myhooks.test:insert(function (foo, bar) print("Test 2", foo, bar) end, 50)
  myhooks.ref3 = myhooks.test:insert(function (foo, bar) print("Test 3", foo, bar) end, 150)
  print"--"
  myhooks.test("Hello", "world")
  myhooks.test:remove(myhooks.ref1)
  print"--"
  myhooks.test("Hello", "world")
  

  Should prove useful. This is similar to how naim does its hooks, although all of the hook glue in naim happens in C. Remaining to do: provide support for writable arguments. Patches thoughtfully accepted. This is part of my "Joshua's Lua Hack of the Day" series, and was originally written on 2007-02-01.

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