_draft1.txt

#### Step 2: Directly calling functions

We learned how to have Moon# calculate a factorial of a number chosen from the outside. But well, done like that smells like a dirty hack (still, it's an important technique we'll use a lot).

Here it's how to call a Lua function from C#.

{% highlight csharp %}

double MoonSharpFactorial()
{
	string scriptCode = @"    
		-- defines a factorial function
		function fact (n)
			if (n == 0) then
				return 1
			else
				return n*fact(n - 1)
			end
		end";

	Script script = new Script();

	script.DoString(scriptCode);

	DynValue luaFactFunction = script.Globals.Get("fact");
	
	DynValue res = script.Call(luaFactFunction, 4);

	return res.Number;
}

{% endhighlight %}

Ok, we changed a little but here things get a lot harder. Let's see what we did.

First of all, we removed the return at the end of the script - we could have kept that, but it was going to be useless as we want to call *fact* with parameters of our choice.

Then we introduced this line:

{% highlight csharp %}
DynValue luaFactFunction = script.Globals.Get("fact");
{% endhighlight %}

This gets the *fact* function from the script globals. You might ask why we didn't just use *script.Globals["fact"]*.. the reason is that the indexer property does a
great job of converting from Moon# values to CLR (C#) objects, but here we want a Moon# value (an object of type DynValue) so we use the Get method which performs no conversions.

After this we can call the function with our chosen number - 4:

{% highlight csharp %}
DynValue res = script.Call(luaFactFunction, 4);
{% endhighlight %}