Re: [Pharo-project] [Pharo-users] Fuel FLMethodChanged error
On Fri, Jun 8, 2012 at 1:41 AM, Paul DeBruicker <pdebruic@gmail.com> wrote:
On 06/07/2012 02:25 PM, Mariano Martinez Peck wrote:
| serializer | serializer := FLSerializer newFull. serializer serialize: xxx on: aStream.
and tell me if that also work?
After loading FuelMetaLevel as Martin suggested the above code works to serialize and materialize the problematic domain objects just fine.
Ok, just to clarify: when you install the package Fuel only, and in your graph you have entities like classes or methods, they will be considered "global", that is, we just store the class name and selector and during materialization we search it in the Smalltalk globals. If the class/method is not present, we throw an error. Now...closures are more complicated because you can even EVALUATE them. If the method surrounding the closure has changed in the image you are materializing, evaluating the closure (depending on the change in the method) can even crash your VM. Because of that, when serializing methods "as globals" we also store a chemsum and we compare during materialization to see that it hasn't change it. If changed, we throw the FLMethodChanged. With the package FuelMetalevel, and by using #newFull the serializer will consider the method as "full" so it will be fully serialized, and therefore you don't have the problem of the checksum. Anyway, you found a bug because you should not be needing FuelMetalevel since you are serializing and materializing in the same image. We will investigate it. Thanks -- Mariano http://marianopeck.wordpress.com
After loading FuelMetaLevel as Martin suggested the above code works to serialize and materialize the problematic domain objects just fine.
Ok, just to clarify: when you install the package Fuel only, and in your graph you have entities like classes or methods, they will be considered "global", that is, we just store the class name and selector and during materialization we search it in the Smalltalk globals. If the class/method is not present, we throw an error. Now...closures are more complicated because you can even EVALUATE them. If the method surrounding the closure has changed in the image you are materializing, evaluating the closure (depending on the change in the method) can even crash your VM. Because of that, when serializing methods "as globals" we also store a chemsum and we compare during materialization to see that it hasn't change it. If changed, we throw the FLMethodChanged. With the package FuelMetalevel, and by using #newFull the serializer will consider the method as "full" so it will be fully serialized, and therefore you don't have the problem of the checksum.
Anyway, you found a bug because you should not be needing FuelMetalevel since you are serializing and materializing in the same image.
Ok...the problem was when you are using the normal (light) serialization with Fuel where methods are always serialized as global. In your case, the method was "not installed" and therefore, was different during materialization. I have just commited Fuel-MarianoMartinezPeck.695. If you know try to serialize again your example, you should get a FLNotInstalledMethod error saying " #XXXSelector can not be serialized as global because it is not installed. You need FuelMetalevel to fully serialize methods. See the documentation. '" And now in http://rmod.lille.inria.fr/web/pier/software/Fuel/Errors I have added that exception and its explanation: * ** FLNotInstalledMethod** By default, Fuel serializes methods as globals. For more details see this page<http://rmod.lille.inria.fr/web/pier/software/Fuel/Version1.8/Documentation/G...>. I am an error produced during serialization, signaled when trying to serialize a method that is not installed in any class. It is a prevention, because such method is lekely to be absent during materialization. This case may happen when serializing closures that hold references to not installed methods. If the user wants to fully serialize methods, then it needs to install the package FuelMetalevel (see this page for explanations<http://rmod.lille.inria.fr/web/pier/software/Fuel/Version1.8/Documentation/F...>) and create the serializer by using the method #newFull. Example:* * FLSerializer newFull serialize: anObject toFileNamed: 'example'.* Cheers
We will investigate it.
Thanks
-- Mariano http://marianopeck.wordpress.com
-- Mariano http://marianopeck.wordpress.com
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Mariano Martinez Peck