From: John Lam <drjflam@...>
Date: 2006-02-11T07:20:54+09:00
Subject: Re: Preserve value-type semantics in imported types

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Thanks, Nori!

Perhaps it wasn't super clear in my example, but this line of code:

p =3D Point.new(3, 4)

actually creates a new CLR Point value type inside of a Ruby VALUE object. =
A
CLR value type is an opaque blob of data (but in this case is really a
couple of 32 bit integers packed together), so I store it in a T_DATA
struct. So I allocate enough memory to hold the value type, and tell the CL=
R
to create the value type at the address of the T_DATA struct in the VALUE
object.

X and Y are properties defined in the Point value type class in the CLR.
They map to accessor methods get/set_X and get/set_Y. My RubyCLR bridge map=
s
these things automagically through liberal use of const_missing and
method_missing. So I can't change these names even if they aren't
Ruby-esque. Those are the case-sensitive method and property names defined
by the value type in the CLR.

I guess the real issue is that I don't think there's a way to force value
type semantics onto Ruby reference types. It would be nice to preserve CLR
value type semantics inside of Ruby, but hey- they're different type system=
s
so you need to abide by the rules of those type systems.

I'm just worried that it might introduce bugs in code that use my bridge:

p1 =3D p2 is just so much more intuitive than p1 =3D p2.clone

If you're curious about my RubyCLR bridge, you can download my first public
drop of the bits here:
http://www.iunknown.com/articles/2006/01/12/first-drop-of-rubyclr

I'm working on a new drop that marshals value types correctly - hence this
question on the list. Hopefully I'll have support early next week for folks
to play with.

Thanks
-John
http://www.iunknown.com

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