From iok at selvaag.no  Wed Apr 25 07:33:39 2007
From: iok at selvaag.no (Iver Odin Kvello)
Date: Wed, 25 Apr 2007 09:33:39 +0200
Subject: [rdnzl-devel] A question about CAST
Message-ID: <554B9CBD8BD19349B0AB0361B42527A8356CC2@SELVAAGXCH01.selvaag.no>

Hello,
 
We've recently started using RDNZL for integration between an internal
application written in ACL 7.0 and a CAD system using a .Net-based
extension-layer in the latter; using .Net Remoting for communicating
between the two systems. We've found that RDNZL works robustly, reliably
and is very easy to use. Thank you very much for creating it.
 
I have a question with regards to the action of the CAST operator:
Currently, when CAST'ing from one .Net class to another, the
type of the container is destructively updated; and there doesn't seem 
to be any way of copying a container so that a reference to the same 
object but with another type can be created.  That is, I'd like to do
something like
 
   (cast foo "SomeType"))
   (setq bar (copy-container foo))
   (cast bar "SomeOtherType"))
 
without the last operating also setting the type of FOO 
to SomeOtherType [1]
 
Is there some idiom that would work like this that I've missed? If
not, I guess the functionality would have to be added at the C++
level, which I haven't really looked at yet. Any pointers would be
appreciated.
 

Iver Odin Kvello
iok at selvaag.no
 
 
[1] The actual situation that came up was this: We have a remote
 object - actually a transparent proxy - of an interface-type WALL,
 and we need to get a reference to its lease. However, to to this we
 must cast the object to MarshalByRefObject, and if we use CAST to get
 this, it is impossible to CAST back to the original interface
 type. We did find a workaround: using
 System.Runtime.Remoting.RemotingServices.GetRealProxy, another copy
 of the transparent proxy is easily obtained, and that can be cast to
 a MBRO instead. But a copy/cast-operator would have been nicer.
 
 
 
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mailman.common-lisp.net/pipermail/rdnzl-devel/attachments/20070425/35aea519/attachment.html>

From edi at agharta.de  Thu Apr 26 08:31:29 2007
From: edi at agharta.de (Edi Weitz)
Date: Thu, 26 Apr 2007 10:31:29 +0200
Subject: [rdnzl-devel] A question about CAST
In-Reply-To: <554B9CBD8BD19349B0AB0361B42527A8356CC2@SELVAAGXCH01.selvaag.no>
	(Iver Odin Kvello's message of "Wed, 25 Apr 2007 09:33:39 +0200")
References: <554B9CBD8BD19349B0AB0361B42527A8356CC2@SELVAAGXCH01.selvaag.no>
Message-ID: <uslanv8ny.fsf@agharta.de>

Hi,

On Wed, 25 Apr 2007 09:33:39 +0200, "Iver Odin Kvello" <iok at selvaag.no> wrote:

> We've recently started using RDNZL for integration between an
> internal application written in ACL 7.0 and a CAD system using a
> .Net-based extension-layer in the latter; using .Net Remoting for
> communicating between the two systems. We've found that RDNZL works
> robustly, reliably and is very easy to use. Thank you very much for
> creating it.

Thanks, that's good to hear.

> I have a question with regards to the action of the CAST operator:
> Currently, when CAST'ing from one .Net class to another, the type of
> the container is destructively updated; and there doesn't seem to be
> any way of copying a container so that a reference to the same
> object but with another type can be created.  That is, I'd like to
> do something like
>  
>    (cast foo "SomeType"))
>    (setq bar (copy-container foo))
>    (cast bar "SomeOtherType"))
>  
> without the last operating also setting the type of FOO to
> SomeOtherType [1]
>
> Is there some idiom that would work like this that I've missed?

I first have to admit that I myself am pretty busy with other stuff at
the moment and that I haven't used RDNZL in earnest for quite some
time, so bear with me if I'm talking nonsense... :)

The answer IIRC is that what you want is currently not supported.

> If not, I guess the functionality would have to be added at the C++
> level, which I haven't really looked at yet. Any pointers would be
> appreciated.

Yes, you'd have to do that at in the C++ code, i.e. create a "copy"
operation in the DotNetContainer class which copies an existing
container and returns (a pointer to) the copy.  And export that
operation so that you can use it from Lisp.  And then make it
available to Lisp via the FFI.  I /think/ that shouldn't be too hard
and shouldn't result in any GC problems.

Of course, if you do that it'd be nice if you could send your
modifications back to the list so I can include it in a future
release:

  http://weitz.de/patches.html

> The actual situation that came up was this: We have a remote object
> - actually a transparent proxy - of an interface-type WALL, and we
> need to get a reference to its lease. However, to to this we must
> cast the object to MarshalByRefObject, and if we use CAST to get
> this, it is impossible to CAST back to the original interface type.

I'm probably too dense at the moment, but /why/ can't you just cast
back?

Cheers,
Edi.


From iok at selvaag.no  Thu Apr 26 15:11:32 2007
From: iok at selvaag.no (Iver Odin Kvello)
Date: Thu, 26 Apr 2007 17:11:32 +0200
Subject: [rdnzl-devel] A question about CAST
In-Reply-To: <uslanv8ny.fsf@agharta.de>
References: <554B9CBD8BD19349B0AB0361B42527A8356CC2@SELVAAGXCH01.selvaag.no>
	<uslanv8ny.fsf@agharta.de>
Message-ID: <c61534450704260811g6e342088w34cdebb1bfb50504@mail.gmail.com>

> Yes, you'd have to do that at in the C++ code, i.e. create a "copy"
> operation in the DotNetContainer class which copies an existing
> container and returns (a pointer to) the copy.  And export that
> operation so that you can use it from Lisp.  And then make it
> available to Lisp via the FFI.  I /think/ that shouldn't be too hard
> and shouldn't result in any GC problems.

Thank you, I'll have a look.

Also: I just realised that there is a very simple additional workaround:
One could just load in an assembly with a class with a static method

 public static Object Copy(Object o) { return o; }

That worked too; but I've installed a C++ setup anyway to try to
understand things better.

> Of course, if you do that it'd be nice if you could send your
> modifications back to the list so I can include it in a future
> release

We will.

>> and if we use CAST to get this, it is impossible to CAST back to the
>> original interface type.

> I'm probably too dense at the moment, but /why/ can't you just cast
> back?

I don't really know why exactly, but the error given is

  Error: .NET error (System.InvalidCastException): Object must
  implement IConvertible.

Regards,
Iver Odin Kvello
iok at selvaag.no


From edi at agharta.de  Thu Apr 26 15:24:32 2007
From: edi at agharta.de (Edi Weitz)
Date: Thu, 26 Apr 2007 17:24:32 +0200
Subject: [rdnzl-devel] A question about CAST
In-Reply-To: <c61534450704260811g6e342088w34cdebb1bfb50504@mail.gmail.com>
	(Iver Odin Kvello's message of "Thu, 26 Apr 2007 17:11:32 +0200")
References: <554B9CBD8BD19349B0AB0361B42527A8356CC2@SELVAAGXCH01.selvaag.no>
	<uslanv8ny.fsf@agharta.de>
	<c61534450704260811g6e342088w34cdebb1bfb50504@mail.gmail.com>
Message-ID: <ufy6nxiof.fsf@agharta.de>

On Thu, 26 Apr 2007 17:11:32 +0200, "Iver Odin Kvello" <iok at selvaag.no> wrote:

> I don't really know why exactly, but the error given is
>
>   Error: .NET error (System.InvalidCastException): Object must
>   implement IConvertible.

Strange.  Does that only happen for certain objects or always if you
try to cast something back and forth?

Thanks,
Edi.


From iok at selvaag.no  Thu Apr 26 15:43:29 2007
From: iok at selvaag.no (Iver Odin Kvello)
Date: Thu, 26 Apr 2007 17:43:29 +0200
Subject: [rdnzl-devel] A question about CAST
In-Reply-To: <ufy6nxiof.fsf@agharta.de>
Message-ID: <554B9CBD8BD19349B0AB0361B42527A8356CC3@SELVAAGXCH01.selvaag.no>


> Strange.  Does that only happen for certain objects or always if you
try to cast something back and forth?

Only for certain objects, but I can reproduce it fairly easily:

RDNZL-USER(5): (import-types "System" "Net.WebClient")
NIL
RDNZL-USER(6): (setf w (new "System.Net.WebClient"))
#<RDNZL::CONTAINER System.Net.WebClient #xda75ac8>
RDNZL-USER(7): (cast w "System.Object")
Error: .NET error (System.InvalidCastException): Object must implement
IConvertible.
  [condition type: RDNZL-ERROR]

I didn't think of it as an issue; I just assumed it was some sort of
.Net restriction.

Iver Odin Kvello
iok at selvaag.no


From iok at selvaag.no  Thu Apr 26 15:59:55 2007
From: iok at selvaag.no (Iver Odin Kvello)
Date: Thu, 26 Apr 2007 17:59:55 +0200
Subject: [rdnzl-devel] A possible bugfix for a possible bug in
	IMPORT-ASSEMBLY
Message-ID: <554B9CBD8BD19349B0AB0361B42527A8356CC4@SELVAAGXCH01.selvaag.no>

I think there is a bug in IMPORT-ASSEMBLY, in that the documentation
says
    
      "Imports all public types of the assembly ASSEMBLY \(a string or a
    CONTAINER).  If ASSEMBLY is a string then the assembly is first
loaded
    with LOAD-ASSEMBLY.  Returns ASSEMBLY as a CONTAINER."

However, it doesn't seem to actually import the public types when the
ASSEMBLY argument isn't
passed to IMPORT-TYPE. Passing the assembly fixes this.
 
 
Iver Odin Kvello
iok at selvaag.no
 
 
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mailman.common-lisp.net/pipermail/rdnzl-devel/attachments/20070426/0f5bad62/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: rdnzl-import.patch
Type: application/octet-stream
Size: 737 bytes
Desc: rdnzl-import.patch
URL: <https://mailman.common-lisp.net/pipermail/rdnzl-devel/attachments/20070426/0f5bad62/attachment.obj>

From edi at agharta.de  Fri Apr 27 07:37:38 2007
From: edi at agharta.de (Edi Weitz)
Date: Fri, 27 Apr 2007 09:37:38 +0200
Subject: [rdnzl-devel] A question about CAST
In-Reply-To: <554B9CBD8BD19349B0AB0361B42527A8356CC3@SELVAAGXCH01.selvaag.no>
	(Iver Odin Kvello's message of "Thu, 26 Apr 2007 17:43:29 +0200")
References: <554B9CBD8BD19349B0AB0361B42527A8356CC3@SELVAAGXCH01.selvaag.no>
Message-ID: <utzv26zel.fsf@agharta.de>

On Thu, 26 Apr 2007 17:43:29 +0200, "Iver Odin Kvello" <iok at selvaag.no> wrote:

> Only for certain objects, but I can reproduce it fairly easily:
>
> RDNZL-USER(5): (import-types "System" "Net.WebClient")
> NIL
> RDNZL-USER(6): (setf w (new "System.Net.WebClient"))
> #<RDNZL::CONTAINER System.Net.WebClient #xda75ac8>
> RDNZL-USER(7): (cast w "System.Object")
> Error: .NET error (System.InvalidCastException): Object must implement
> IConvertible.
>   [condition type: RDNZL-ERROR]
>
> I didn't think of it as an issue; I just assumed it was some sort of
> .Net restriction.

Yes, it is - I checked the .NET documentation.  Thanks for the info.


From edi at agharta.de  Fri Apr 27 07:46:53 2007
From: edi at agharta.de (Edi Weitz)
Date: Fri, 27 Apr 2007 09:46:53 +0200
Subject: New release 0.10.9   (Was: [rdnzl-devel] A possible bugfix for a
	possible bug in IMPORT-ASSEMBLY)
In-Reply-To: <554B9CBD8BD19349B0AB0361B42527A8356CC4@SELVAAGXCH01.selvaag.no>
	(Iver Odin Kvello's message of "Thu, 26 Apr 2007 17:59:55 +0200")
References: <554B9CBD8BD19349B0AB0361B42527A8356CC4@SELVAAGXCH01.selvaag.no>
Message-ID: <ups5q6yz6.fsf@agharta.de>

On Thu, 26 Apr 2007 17:59:55 +0200, "Iver Odin Kvello" <iok at selvaag.no> wrote:

> I think there is a bug in IMPORT-ASSEMBLY

Yes, you're right, thanks.  I've released a new version with your
patch incorporated.