Dealing with Exceptions

There are some .NET methods which will throw exceptions on error. These are converted into regular Lua errors by LuaInterface, so you need to execute these methods in a protected call to avoid your program crashing. For instance, load_assembly usually loads assemblies from the Global Assembly Cache (GAC) but it will work with your own assemblies if you end them with an explicit '.dll'.

However, it will not load an assembly given an arbitrary path. This is not difficult to get around, but the function we need is one of those that throw exceptions. Consider this script:

-- load.lua
require "CLRPackage"
import "System.Reflection"
function get_assembly_name(name)
    local res
    local suc,err = pcall(function()
        res = AssemblyName.GetAssemblyName(name)
    if suc then
        return res
        return nil,err

GetAssemblyName returns an object which you can pass to Assembly.Load, but we have to call it using pcall. pcall will usually just return true, but if an error occured it returns false,error. In effect, this is Lua's try..catch mechanism. The variable err will contain the exception thrown and the message from the exception in string format.