Lua launcher for shortcuts

-- WTF: this is lua script launcher for shortcuts or debugging

-- Usage: run in shell:
-- path/to/lua/executable /path/to/this/launcher.lua /path/to/script.lua

-- Example: notepad++ shortcut looks like this (alt + f1):
-- <Command name="Lua" Ctrl="no" Alt="yes" Shift="no" Key="112">
--   luajit c:\lua\launcher.lua $(FULL_CURRENT_PATH)
-- </Command>

-- Features:
-- 1. Console window doesn't disappear, we can debug script after launch
-- 2. Package paths configured for [/path/to/script.lua], run it like project
-- 3. Sweet traceback!

-- Tricks: write 'cont' on 'lua_debug' mode

-- Written by snus (C) for internal corporate usage, if you see it - go to jail now.

local path_sep   = package.config:sub(1, 1)
local shared_ext = path_sep == '\\' and 'dll' or 'so'

-- shift args back
for i = 0, #arg do
    arg[i] = arg[i + 1]
end

-- Init path
local scrPath = arg[0] or os.exit()
scrPath = scrPath:gsub('[\\/]', '/')

local __path, __name = scrPath:match'^(.*)/(.-).lua$'
local __name_ext     = __name .. '.lua'

package.path  = __path..'/?/init.lua;' .. package.path
package.path  = __path..'/?.lua;'      .. package.path
package.cpath = __path..'/?/core.' .. shared_ext .. ';' .. package.cpath
package.cpath = __path..'/?.'      .. shared_ext .. ';' .. package.cpath

package.path  = package.path:gsub('[\\/]', path_sep)
package.cpath = package.cpath:gsub('[\\/]', path_sep)

local function errorprinter(msg, layer)
  -- if it's nil or something
    msg = tostring(msg)

    local trace = debug.traceback(msg, 1 + (layer or 1))
    trace = trace:gsub('%[string "' .. __name_ext .. '"%]', __name_ext)

    -- cut four last lines of traceback
    local lines = ('\n[^\n]+'):rep(4) .. '$'
    trace = trace:gsub(lines, "")

    print("Error: " .. trace)
end

xpcall(function()
        local file = io.open(scrPath)
        local code = file:read('*a'); file:close()
        local chunk, err = loadstring(code, __name_ext)
        if not chunk then error(err, 2) end
        chunk()
    end,
    errorprinter
)

-- term window is not closed at end of task
debug.debug()