Hey, you're one up on IronRuby, which had a bug where one couldn't create an
instance of a CLR struct!
http://ironruby.codeplex.com/WorkItem/View.aspx?WorkItemId=1788
On Wed, Sep 30, 2009 at 3:45 AM, David Miller <dmiller2...@gmail.com> wrote:
>
> Short answer: It's a bug.
> Longer answer: It's a problem with type propagation in let. It'll
> take me a day or so to fix it.
>
> The handling of non-primitive value types by the compiler still has
> some problems. Any place where the JVM compiler is discriminating
> between primitive types and reference types, the CLR compiler needs to
> discriminate between primitive types, non-primitive value types and
> reference types. I need to make a pass back through the compiler code
> and make sure I catch all the places where it matters. I'll put this
> at the top of the list.
>
> Boring detail for the very curious: At the moment, your (a) works
> because it uses reflection and (a2) fails because it is trying to do
> the right thing. The (doto) expands into a let that introduces a box
> followed by a cast that causes the struct to be copied. The .Scale is
> applied to the copy. That's why you don't see the change. In C#, the
> compiled code looks like:
>
> (a) looks like:
> object target = new Matrix();
> object[] args = new object[] {2.0, 3.0 };
> Reflector.CallInstanceMethod("Scale", target, args);
> return target;
>
> (a2) looks like:
>
> object obj2 = new Matrix();
> ((Matrix) obj2).Scale(2.0, 3.0);
> return obj2;
>
> I need to make (a2) look like:
>
> Matrix obj2 = new Matrix();
> obj2.Scale(2.0, 3.0);
> return obj2;
>
>
> -David
>
>
>
>
> On Sep 29, 9:55 am, Shawn Hoover <shawn.hoo...@gmail.com> wrote:
> > Updates to local CLR struct instances seem to be lost as soon as they're
> > made. Is this expected? In the test below, function a2 returns the
> identity
> > matrix despite my attempt to scale it. Function a passes the newly
> > constructed matrix to another function to do the scaling, and it returns
> the
> > scaled matrix as desired. UriBuilder is a class and works either way.
> >
> > (System.Reflection.Assembly/Load "WindowsBase, Version=3.0.0.0,
> > Culture=neutral, PublicKeyToken=31bf3856ad364e35")
> > (import '(System.Windows.Media Matrix))
> > (import '(System UriBuilder))
> >
> > ; Test struct
> > (defn b [matrix] (doto matrix (.Scale 0.5 -0.5)))
> > (defn a [] (b (Matrix.)))
> >
> > (defn a2 [] (doto (Matrix.) (.Scale 0.5 -0.5)))
> >
> > ; Test class
> > (defn b3 [builder] (doto builder (.set_Port 9090)))
> > (defn a3 [] (b3 (UriBuilder.)))
> >
> > (defn a4 [] (doto (UriBuilder.) (.set_Port 9090)))
> >
> > (println "Matrix struct" (a) (a2)
> > (= (a) (a))
> > (= (a2) (a2))
> > (= (a) (a2))) ; True True False
> > (println "UriBuilder class "(a3) (a4)
> > (= 9090 (.Port (a3)) (.Port (a3)))
> > (= 9090 (.Port (a4)) (.Port (a4)))
> > (= 9090 (.Port (a3)) (.Port (a4)))) ; True True True
> >
>
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