[IronPython] Question about serialization

[Curt Hagenlocher]

Ooh, I was unaware of __reduce__ and __reduce_ex__; thanks.


On Wed, Mar 26, 2008 at 8:36 AM, Dino Viehland <dinov at exchange.microsoft.com>
wrote:

>  Unfortunately I don't think what you want will work.  If it's your .NET
> class you could implement __reduce_ex__ and I think we'd pick it up and use
> that for the serialization.  But if it's some arbitrary framework class then
> you'll run into trouble.  On IronPython 2.0 you could have an extension
> class w/ the __reduce_ex__ function, have an ExtensionTypeAttribute that
> links the .NET base class and the extension class, and then call
> RuntimeHelpers.RegisterAssembly and we'd pick up the extension method.
>
>
>
> Also, we do have a feature request for this on CodePlex:
> http://www.codeplex.com/IronPython/WorkItem/View.aspx?WorkItemId=13401
> Voting on it would raise its priority and we'd be more likely to do it
> sooner rather than later.
>
>
>
> *From:* users-bounces at lists.ironpython.com [mailto:
> users-bounces at lists.ironpython.com] *On Behalf Of *Paul Turbett
> *Sent:* Wednesday, March 26, 2008 4:56 AM
> *To:* Discussion of IronPython
> *Subject:* Re: [IronPython] Question about serialization
>
>
>
> Thanks Michael for the advice. Must appreciated. Unfortunately I hasn't
> worked out yet tho :(
>
> I can use pickle from C# using Evaluate, or from within a Python class, on
> a "pure" Python object. However any attempt at pickling a python object that
> derives from a C# base result in an exception like this:
> Cannot convert MyObject(<MyObject object at 0x000000000000002B>) to Int32
>
> Exploring further, I came across Ops.GetDynamicType() and
> Ops.GetAttrsNames() which I thought might be helpful to get the attributes
> of an object and serialize it somehow (manually), but GetAttrNames requires
> an ICallerContext, and I can't see how to get one of those.
>
> It seems that whilst serializing .NET classes is trivial, and serializing
> python classes is trivial, serializing something that touches both is
> proving quite difficult.
>
> Any further suggestions gratefully received!
>
> Thanks, Paul
>
> Michael Foord wrote:
>
> Paul Turbett wrote:
>
>
>
> Hi,
>
>
>
> I'm using IP as a scripting engine in a C# app. I have various Python
>
> classes that derive from a C# base class, and have there own additional
>
> data & functionality.
>
>
>
> I would like to be able to serialize instances of the Python classes
>
> from the C# host for persistence across sessions. Using the standard
>
> BinaryFormatter with the Serializable attribute is not working - I get
>
> an error about the python class not being marked as serializable (the C#
>
> base class is marked as serializable though).
>
>
>
> How can I serialize python objects from C#? Should I use reflection to
>
> roll my own serializer, or is there something in one of the lesser
>
> documented assemblies like Ops I should use?
>
>
>
>
>
>
>
> Typically for serializing Python objects you would use pickle [1]. The
>
> 'dumps' function returns a string (make sure you use the text protocol
>
> for IronPython).
>
>
>
> You could then execute code inside the Python engine to serialize /
>
> deserialize objects. I've not tried this for instances that inherit from
>
> C# base classes - but it should work fine. :-)
>
>
>
> Michael Foord
>
> http://www.ironpythoninaction.com
>
>
>
> .. [1] http://docs.python.org/lib/module-pickle.html
>
>
>
>
>
> I'm using IP 1.1.1 (but will move to 2.0 if that will help). Any
>
> pointers & advice greatly appreciated!
>
>
>
> Thanks, Paul
>
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