Lua_01 - List of Predefined (Global) Variables

"Lua_01" displays name and type (or content) of any predefined ("intrinsic") global Lua variables. In order to "beautify" the output a bit, the variable names are sorted alphabetically and positioned right justified in the list. Extremely long names (and variable contents) are truncated and marked as such with a trailing ellipsis ("...").

Again, the program is simple enough not to require any further description. "Lua_01" should be started without any command line arguments

  lua Lua_01.lua

and yields the following output:

  Lua_01 - lists all (predefined) global variables in Lua 4.0

  list of global variables:
          "_ALERT": (function)
   "_ERRORMESSAGE": (function)
          "_INPUT": (userdata)
         "_OUTPUT": (userdata)
         "_STDERR": (userdata)
          "_STDIN": (userdata)
         "_STDOUT": (userdata)
        "_VERSION": "Lua 4.0"
             "abs": (function)
          "accept": (function)
            "acos": (function)
        "appendto": (function)
           "ascii": (function)
            "asin": (function)
          "assert": (function)
            "atan": (function)
           "atan2": (function)
            "bind": (function)
            "call": (function)
            "ceil": (function)
           "clock": (function)
           "close": (function)
       "closefile": (function)
  "collectgarbage": (function)
         "connect": (function)
  "copytagmethods": (function)
             "cos": (function)
            "date": (function)
           "debug": (function)
             "deg": (function)
          "dofile": (function)
        "dostring": (function)
           "error": (function)
         "execute": (function)
            "exit": (function)
             "exp": (function)
           "floor": (function)
           "flush": (function)
         "foreach": (function)
        "foreachi": (function)
      "foreachvar": (function)
          "format": (function)
           "frexp": (function)
          "gcinfo": (function)
         "getargs": (function)
          "getenv": (function)
       "getglobal": (function)
         "getinfo": (function)
        "getlocal": (function)
            "getn": (function)
     "getpeername": (function)
     "getsockname": (function)
    "gettagmethod": (function)
         "globals": (function)
            "gsub": (function)
           "ldexp": (function)
             "log": (function)
           "log10": (function)
             "max": (function)
             "min": (function)
             "mod": (function)
          "newtag": (function)
            "next": (function)
         "nextvar": (function)
        "openfile": (function)
              "PI": 3.141592653589793
           "print": (function)
             "rad": (function)
          "random": (function)
      "randomseed": (function)
          "rawget": (function)
    "rawgetglobal": (function)
     "rawgettable": (function)
          "rawset": (function)
    "rawsetglobal": (function)
     "rawsettable": (function)
            "read": (function)
        "readfrom": (function)
         "receive": (function)
     "receivefrom": (function)
          "remove": (function)
          "rename": (function)
            "seek": (function)
          "select": (function)
            "send": (function)
          "sendto": (function)
     "setcallhook": (function)
       "setglobal": (function)
     "setlinehook": (function)
        "setlocal": (function)
       "setlocale": (function)
          "settag": (function)
    "settagmethod": (function)
             "sin": (function)
            "sort": (function)
            "sqrt": (function)
         "strbyte": (function)
         "strchar": (function)
         "strfind": (function)
          "strlen": (function)
        "strlower": (function)
          "strrep": (function)
          "strsub": (function)
        "strupper": (function)
             "tag": (function)
             "tan": (function)
         "tinsert": (function)
         "tmpname": (function)
      "tohostname": (function)
            "toip": (function)
        "tonumber": (function)
        "tostring": (function)
         "tremove": (function)
            "type": (function)
       "udpsocket": (function)
         "valueOf": (function)
           "write": (function)
         "writeto": (function)

Most of the entries shown above represent intrinsic functions - if you analyze the list a bit more carefully, you may recognize that the run-time environment used for testing this example program already includes the LuaSocket package...

Source Code

The source code of this example is available for download:

• Lua_01.lua (ASCII file, 4910 bytes)

References