EyeInspector with subclasses of ProtoObject
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EyeInspector with subclasses of ProtoObject
 
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I'm dealing with the MessageArchiver of GLORP which is a subclass of
ProtoObject and handles the "transparent" creation of expressions vía a DNU resolution. The problem I'm facing is that the EyeInspector expects the value in its value holder to respond to #basicSize, and because MessageArchiver inherits from ProtoObject it doesn't understand it. The problem is here: EyeInspector>>#variableFieldsToShow "Answers the indexes of the variable fields of the object to show. Shorten the list for very long collection (cf limit1 and limit2)" |bSize| bSize := self objectVariableSize. ^ bSize <= (self limit1 + self limit2) ifTrue: [1 to: bSize] ifFalse: [(1 to: self limit1) , (bSize - self limit2 + 1 to: bSize)]. If I implement #basicSize in MessageArchiver things go bananas. If I doesn't, and because #objectVariableSize is sent to MessageAchiver "proxy", bSize ends up with an instance of the MessageArchiver instead of an integer. I implemented #inspectorClass in MessageArchiver class to return EyeBasicInspector, but it is the same. Question: Is it documented what I should define/override in my classes to support EyeInspector? Regards, Esteban A. Maringolo pd: Stack trace =========== UndefinedObject(Object)>>error: MessageArchiver>>mustBeBoolean EyeBasicInspector(EyeInspector)>>variableFieldsToShow EyeBasicInspector(EyeInspector)>>addVariableFields: EyeBasicInspector(EyeInspector)>>generateElements EyeBasicInspector(EyeInspector)>>updateList EyeBasicInspector(EyeInspector)>>objectChanged [ self objectChanged ] in EyeBasicInspector(EyeAbstractInspector)>>initializePresenter in Block: [ self objectChanged ] BlockClosure>>cull: BlockClosure>>cull:cull: BlockClosure>>cull:cull:cull: BlockClosure>>cull:cull:cull:cull: |
Re: EyeInspector with subclasses of ProtoObject
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Hi Esteban, I think EyeInspector needs to handle classes that don't inherit from Object specially. Instead of asking the instance it should ask the class. You should be able to use the Context methods for mirror primitives to extract state without sending messages to the instance. Then the special version of EyeInspector for ProtoObject subclasses can ask this like (thisContext objectClass: object) isIndexable ifTrue: [size := thisContext objectSize: object] Basically both the Inspector and the Debugger's execution simulation machinery need to treat encapsulators such as MessageArchiver with kid gloves. One *must not* cause inspecting or debugging to send messages through the encapsulator. Instead, all access to the object should be through primitives that don't send messages to the objects. HTH On Tue, Nov 17, 2015 at 7:05 AM, Esteban A. Maringolo <[hidden email]> wrote: I'm dealing with the MessageArchiver of GLORP which is a subclass of _,,,^..^,,,_ best, Eliot |
Re: EyeInspector with subclasses of ProtoObject
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Inspector: a surgery tool to see inside the objects Debugger: a surgery tool to see inside the processes - or maybe to see how the object live from the inside ;)2015-11-17 18:37 GMT+01:00 Eliot Miranda <[hidden email]>:
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Re: EyeInspector with subclasses of ProtoObject
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In reply to this post by Eliot Miranda-2
2015-11-17 14:37 GMT-03:00 Eliot Miranda <[hidden email]>: Yes, an special inspector for ProtoObject subclasses would be required, but I couldn't find one already suited for this purpose. > (thisContext objectClass: object) isIndexable ifTrue: I don't know if your code was meant to be accurate or just a guideline of how this could be implemented, but Context doesn't implement #objectClass: nor #objectSize: > Basically both the Inspector and the Debugger's execution simulation I know that dealing with Proxies and similar objects is tricky, I had to deal with my own subclasses of ProtoObject in Dolphin, but there the class implemented all that was needed to interact with the environment tools. Hiwever, to me all this is a kind of black magic, I read the blue book years ago and can understand it, but I do understand it as I understand the mechanics of my car, however when it breaks down I take it to the specialist :) Esteban A. Maringolo |
Re: EyeInspector with subclasses of ProtoObject
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Hi Esteban,
On Tue, Nov 17, 2015 at 1:37 PM, Esteban A. Maringolo <[hidden email]> wrote:
Find attached. I think you'll find they are in the Spur version. You might think of back-porting their use in Context form Spur; that'll make the debugger able to handle proxies.
Well, the thing to think of is that inside the VM objects are just a sequence of words, and the VM, while it sends messages, doesn't send messages to objects to update their state; it just accesses the state directly. So in an execution simulation method such as Context methods for instruction decoding pushReceiverVariable: offset self push: (receiver instVarAt: offset + 1) that will send the message instVarAt: to the receiver, and if the receiver is a proxy, that will go through the proixie's doesNotUnderstand: method and send instVarAt: the the object the proxy wraps, which won't do the right thing at all. Instead it needs to be written Context methods for instruction decoding pushReceiverVariable: offset self push: (self object: receiver instVarAt: offset + 1) which reaches into the object without sending any messages to it. I understand that this will appear in Spur, because I made it part of the bootstrap, but if I were you I would integrate these changes into the current version asap. The debugger won't work properly with proxies, encapsulators etc otherwise. _,,,^..^,,,_ best, Eliot |
Context-mirror primitives.st (7K)
Re: EyeInspector with subclasses of ProtoObject
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Hello, This is known and was discussed on the bug tracker. The problem is that currently Pharo has many tools and classes: EyeInspector in the debugger, GTInspector outside, the debugger itself, the in-image interpreter in the Context class ... that need to be changed to support debugging objects that basically cannot receive any message. We are aware of the solution but fixing it for all the toolkits and classes is quite some work. In addition, if not tested, someone will break it because he won't understand that an inspected object can't receive any message because the expected behavior of an object with no DNU behavior and no methods inherited from Object is to freeze the system. It's a lot of fun doing that though. Clement 2015-11-17 21:39 GMT-03:00 Eliot Miranda <[hidden email]>:
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Re: EyeInspector with subclasses of ProtoObject
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I’d like to discuss also the possibility to add those low level operations on mirrors objects, that could be packaged separately from the kernel of the language. Adding them on a first step is easy, then making all tools use them is the hard/timeconsuming part, yes.
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Re: EyeInspector with subclasses of ProtoObject
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In reply to this post by Eliot Miranda-2
Hi Elliot,
2015-11-17 21:39 GMT-03:00 Eliot Miranda <[hidden email]>: > Hi Esteban, > > On Tue, Nov 17, 2015 at 1:37 PM, Esteban A. Maringolo <[hidden email]> > wrote: >> > (thisContext objectClass: object) isIndexable ifTrue: >> > [size := thisContext objectSize: object] >> I don't know if your code was meant to be accurate or just a guideline of >> how this could be implemented, but Context doesn't implement #objectClass: >> nor #objectSize: > Find attached. I think you'll find they are in the Spur version. You might > think of back-porting their use in Context form Spur; that'll make the > debugger able to handle proxies. I added your methods to Context and created a EyeProtoInspector class which uses the mirror methods to access the object size and class. So far it works, or at least doesn't give me walkbalks, but if you do a little more than that you'll get fireworks :) >> I know that dealing with Proxies and similar objects is tricky, I had to >> deal with my own subclasses of ProtoObject in Dolphin, but there the class >> implemented all that was needed to interact with the environment tools. > Well, the thing to think of is that inside the VM objects are just a > sequence of words, and the VM, while it sends messages, doesn't send > messages to objects to update their state; it just accesses the state > directly. So in an execution simulation method such as > > [snip] > > which reaches into the object without sending any messages to it. I > understand that this will appear in Spur, because I made it part of the > bootstrap, but if I were you I would integrate these changes into the > current version asap. The debugger won't work properly with proxies, > encapsulators etc otherwise. Yes, it doesn't right now, but not only for the debugger, but the problem as stated in other mails is with the tools, that seems to be designed without considering these special cases. Regards! Esteban A. Maringolo |
Re: EyeInspector with subclasses of ProtoObject
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In reply to this post by Clément Béra
Hi Clement,
Do you know which is the issue that covers this? I remember complaining about dealing with Proxies in the debugger a year ago and getting a similar response. How does this play with the new "slot based" variables? Regards! Esteban A. Maringolo 2015-11-18 8:35 GMT-03:00 Clément Bera <[hidden email]>: > Hello, > > This is known and was discussed on the bug tracker. > > The problem is that currently Pharo has many tools and classes: EyeInspector > in the debugger, GTInspector outside, the debugger itself, the in-image > interpreter in the Context class ... that need to be changed to support > debugging objects that basically cannot receive any message. > > We are aware of the solution but fixing it for all the toolkits and classes > is quite some work. In addition, if not tested, someone will break it > because he won't understand that an inspected object can't receive any > message because the expected behavior of an object with no DNU behavior and > no methods inherited from Object is to freeze the system. > > It's a lot of fun doing that though. > > Clement > > 2015-11-17 21:39 GMT-03:00 Eliot Miranda <[hidden email]>: >> >> Hi Esteban, >> >> On Tue, Nov 17, 2015 at 1:37 PM, Esteban A. Maringolo >> <[hidden email]> wrote: >>> >>> 2015-11-17 14:37 GMT-03:00 Eliot Miranda <[hidden email]>: >>> > Hi Esteban, >>> > >>> > I think EyeInspector needs to handle classes that don't inherit from >>> > Object specially. Instead of asking the instance it should ask the >>> > class. >>> > You should be able to use the Context methods for mirror primitives to >>> > extract state without sending messages to the instance. Then the >>> > special >>> > version of EyeInspector for ProtoObject subclasses can ask this like >>> >>> Yes, an special inspector for ProtoObject subclasses would be required, >>> but I couldn't find one already suited for this purpose. >>> >>> > (thisContext objectClass: object) isIndexable ifTrue: >>> > [size := thisContext objectSize: object] >>> >>> I don't know if your code was meant to be accurate or just a guideline of >>> how this could be implemented, but Context doesn't implement #objectClass: >>> nor #objectSize: >> >> >> Find attached. I think you'll find they are in the Spur version. You >> might think of back-porting their use in Context form Spur; that'll make the >> debugger able to handle proxies. >> >>> > Basically both the Inspector and the Debugger's execution simulation >>> > machinery need to treat encapsulators such as MessageArchiver with kid >>> > gloves. One *must not* cause inspecting or debugging to send messages >>> > through the encapsulator. Instead, all access to the object should be >>> > through primitives that don't send messages to the objects. >>> >>> I know that dealing with Proxies and similar objects is tricky, I had to >>> deal with my own subclasses of ProtoObject in Dolphin, but there the class >>> implemented all that was needed to interact with the environment tools. >>> >>> Hiwever, to me all this is a kind of black magic, I read the blue book >>> years ago and can understand it, but I do understand it as I understand the >>> mechanics of my car, however when it breaks down I take it to the specialist >>> :) >> >> Well, the thing to think of is that inside the VM objects are just a >> sequence of words, and the VM, while it sends messages, doesn't send >> messages to objects to update their state; it just accesses the state >> directly. So in an execution simulation method such as >> >> Context methods for instruction decoding >> pushReceiverVariable: offset >> self push: (receiver instVarAt: offset + 1) >> >> that will send the message instVarAt: to the receiver, and if the receiver >> is a proxy, that will go through the proixie's doesNotUnderstand: method and >> send instVarAt: the the object the proxy wraps, which won't do the right >> thing at all. Instead it needs to be written >> >> Context methods for instruction decoding >> pushReceiverVariable: offset >> self push: (self object: receiver instVarAt: offset + 1) >> >> which reaches into the object without sending any messages to it. I >> understand that this will appear in Spur, because I made it part of the >> bootstrap, but if I were you I would integrate these changes into the >> current version asap. The debugger won't work properly with proxies, >> encapsulators etc otherwise. >> >> _,,,^..^,,,_ >> best, Eliot > > |
Re: EyeInspector with subclasses of ProtoObject
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In reply to this post by Guillermo Polito
2015-11-18 8:43 GMT-03:00 Guillermo Polito <[hidden email]>:
All the needed operations already exist. You can put them on your mirror objects without any problem.
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Re: EyeInspector with subclasses of ProtoObject
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2015-11-18 13:29 GMT-03:00 Clément Bera <[hidden email]>:
> > > 2015-11-18 8:43 GMT-03:00 Guillermo Polito <[hidden email]>: >> >> I’d like to discuss also the possibility to add those low level operations >> on mirrors objects, that could be packaged separately from the kernel of the >> language. Adding them on a first step is easy, then making all tools use >> them is the hard/timeconsuming part, yes. > > > All the needed operations already exist. You can put them on your mirror > objects without any problem. Who takes the decision to put it either in EyeInspector or GtInspector? Regards! |
Re: EyeInspector with subclasses of ProtoObject
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In reply to this post by Clément Béra
I know we can :) and I did some prototypes already as part of my thesis.
The question is if that is a design we *want* or not.
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Re: EyeInspector with subclasses of ProtoObject
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On 19-11-15 10:33, Guillermo Polito wrote:
> I know we can :) and I did some prototypes already as part of my thesis. > > The question is if that is a design we *want* or not. 1 Is it an improvement on the current situation? 2 Is it blocking an improvement direction we want to take? 3 Can it be tested quickly? Stephan |
Re: EyeInspector with subclasses of ProtoObject
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2015-11-19 7:22 GMT-03:00 Stephan Eggermont <[hidden email]>:
> On 19-11-15 10:33, Guillermo Polito wrote: >> >> I know we can :) and I did some prototypes already as part of my thesis. >> >> The question is if that is a design we *want* or not. > > > 1 Is it an improvement on the current situation? Yes. > 2 Is it blocking an improvement direction we want to take? Debugging/Inspecting Proxies and other ProtoObjects is barely supported by the current tools. > 3 Can it be tested quickly? No idea. Esteban A. Maringolo |
Re: EyeInspector with subclasses of ProtoObject
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In reply to this post by Esteban A. Maringolo
Hi,
Please tell me more specifically what needs to be done. Could you give me a concrete example of an object that cannot be inspected? Cheers, Tudor > On Nov 18, 2015, at 6:08 PM, Esteban A. Maringolo <[hidden email]> wrote: > > 2015-11-18 13:29 GMT-03:00 Clément Bera <[hidden email]>: >> >> >> 2015-11-18 8:43 GMT-03:00 Guillermo Polito <[hidden email]>: >>> >>> I’d like to discuss also the possibility to add those low level operations >>> on mirrors objects, that could be packaged separately from the kernel of the >>> language. Adding them on a first step is easy, then making all tools use >>> them is the hard/timeconsuming part, yes. >> >> >> All the needed operations already exist. You can put them on your mirror >> objects without any problem. > > > Who takes the decision to put it either in EyeInspector or GtInspector? > > Regards! > -- www.tudorgirba.com "Be rather willing to give than demanding to get." |
Re: EyeInspector with subclasses of ProtoObject
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In reply to this post by Guillermo Polito
2015-11-19 10:33 GMT+01:00 Guillermo Polito <[hidden email]>:
There is a misunderstanding. I am not talking about prototypes. The operations are in the production VM and are stable. That's why I say you can use it. There is no need to implement additional VM support to debug this kind of objects as it's already done and stable.
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Re: EyeInspector with subclasses of ProtoObject
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In reply to this post by Tudor Girba-2
2015-11-19 15:31 GMT+01:00 Tudor Girba <[hidden email]>: Hi, Try this code: GTInspector inspect: ProtoObject new Then you can try with instance of subclasses of ProtoObjects with different properties. For example: ProtoObject variableSubclass: #ProtoArray instanceVariableNames: '' classVariableNames: '' category: 'Kernel-Objects' GTInspector inspect: (ProtoArray new: 3) Lastly you can try the hard cases. For example run: ProtoArray superclass: nil. GTInspector inspect: (ProtoArray new: 3)The generic problem is that these objects cannot be expected to answer any message, as it can crash the VM, so inspection should happen without the object inspected receiving any message.
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Re: EyeInspector with subclasses of ProtoObject
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In reply to this post by Tudor Girba-2
Hi,
I looked at the problem with Esteban. Essentially, we would benefit a lot from the Context mirror methods that Eliot sent. We can still imagine a mirror object on top of that, but already they would provide a good enough support. Do we agree to add these methods to Pharo? Cheers, Doru > On Nov 19, 2015, at 3:31 PM, Tudor Girba <[hidden email]> wrote: > > Hi, > > Please tell me more specifically what needs to be done. Could you give me a concrete example of an object that cannot be inspected? > > Cheers, > Tudor > > >> On Nov 18, 2015, at 6:08 PM, Esteban A. Maringolo <[hidden email]> wrote: >> >> 2015-11-18 13:29 GMT-03:00 Clément Bera <[hidden email]>: >>> >>> >>> 2015-11-18 8:43 GMT-03:00 Guillermo Polito <[hidden email]>: >>>> >>>> I’d like to discuss also the possibility to add those low level operations >>>> on mirrors objects, that could be packaged separately from the kernel of the >>>> language. Adding them on a first step is easy, then making all tools use >>>> them is the hard/timeconsuming part, yes. >>> >>> >>> All the needed operations already exist. You can put them on your mirror >>> objects without any problem. >> >> >> Who takes the decision to put it either in EyeInspector or GtInspector? >> >> Regards! >> > > -- > www.tudorgirba.com > > "Be rather willing to give than demanding to get." > > > -- www.tudorgirba.com "Yesterday is a fact. Tomorrow is a possibility. Today is a challenge." |
Re: EyeInspector with subclasses of ProtoObject
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In reply to this post by Clément Béra
Yep. Got it. See my other mail about integrating the reflection methods in Context. This would be enough to get the GTInspector working properly (we already did it but we cannot commit because of missing Context methods).
Cheers, Doru > On Nov 19, 2015, at 5:53 PM, Clément Bera <[hidden email]> wrote: > > > > 2015-11-19 15:31 GMT+01:00 Tudor Girba <[hidden email]>: > Hi, > > Please tell me more specifically what needs to be done. Could you give me a concrete example of an object that cannot be inspected? > > Try this code: > > GTInspector inspect: ProtoObject new > > Then you can try with instance of subclasses of ProtoObjects with different properties. For example: > > ProtoObject variableSubclass: #ProtoArray > instanceVariableNames: '' > classVariableNames: '' > category: 'Kernel-Objects' > > GTInspector inspect: (ProtoArray new: 3) > > Lastly you can try the hard cases. For example run: > > ProtoArray superclass: nil. > GTInspector inspect: (ProtoArray new: 3) > > The generic problem is that these objects cannot be expected to answer any message, as it can crash the VM, so inspection should happen without the object inspected receiving any message. > > > Cheers, > Tudor > > > > On Nov 18, 2015, at 6:08 PM, Esteban A. Maringolo <[hidden email]> wrote: > > > > 2015-11-18 13:29 GMT-03:00 Clément Bera <[hidden email]>: > >> > >> > >> 2015-11-18 8:43 GMT-03:00 Guillermo Polito <[hidden email]>: > >>> > >>> I’d like to discuss also the possibility to add those low level operations > >>> on mirrors objects, that could be packaged separately from the kernel of the > >>> language. Adding them on a first step is easy, then making all tools use > >>> them is the hard/timeconsuming part, yes. > >> > >> > >> All the needed operations already exist. You can put them on your mirror > >> objects without any problem. > > > > > > Who takes the decision to put it either in EyeInspector or GtInspector? > > > > Regards! > > > > -- > www.tudorgirba.com > > "Be rather willing to give than demanding to get." > > > > > -- www.tudorgirba.com "Problem solving efficiency grows with the abstractness level of problem understanding." |
Re: EyeInspector with subclasses of ProtoObject
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In reply to this post by Clément Béra
Nope :) I understood you well. And yes, you misunderstood my answer :P. I know that the VM already provides the necessary primitives and I know how to use them ^^.
I meant prototypes of mirrors on the image side. I know and used the primitives. The questions are if we want to have a mirror library, if we want core tools (such as the inspector) to use it instead of delegating reflective operations to objects. Also there are many different mirror designs we can come up with. The design I have in mind is pretty much aligned with the idea of mirrors that Camille has in mind where there are low level mirrors to manipulate objects as the VM know them, and then high level mirrors implementing the language concerns AND application specific mirrors. But then this kind of mirror implementation is a beast in itself :) Also, answering Stephan Eggermont below: 1 Is it an improvement on the current situation? I believe it is. Mirrors allow to extract the reflective behavior in separate objects. With them we would be able to inspect instances of classes that have no methods at all. Moreover, it would clean up objects’ API because there will be no more meta-level methods in the base classes. This would avoid name clashes like #name in metaclasses that was discussed the other day. 2 Is it blocking an improvement direction we want to take? I do not completely understand the question. I just can say that I think having mirrors is an interesting direction. 3 Can it be tested quickly? A basic mirror implementation that only exposes VM internals could be easy to implement and test. Adapting the eye inspector to use a mirror instead of a normal object is also fairly easy, at lest for a first implementation. Of course the question always is doing it for real: I do not know how much time would it take to make all tools work as well.
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