April 2019 - Pharo-users - lists.pharo.org

Re: [Pharo-users] ARM vm limitations ?
by Mariano Martinez Peck April 10, 2019

April 10, 2019

On Mon, Mar 18, 2019 at 8:26 AM Albrecht Baur via Pharo-users < pharo-users(a)lists.pharo.org> wrote: > Hi, I'd like to play around with pharo on ARM devices (like a > HummingBoard, the ones from ODROID or one of the beagleboards). But I am > not sure if I have to take care of the ARM architecture version (ARMv6 / > ARMv7 / ARMv8) when choosing my toy. > > I found this vm: > http://files.pharo.org/vm/pharo-spur32/linux/armv6/ > Is it only for armv6 like the folder name says or is ARMv7 and ARMv8 > working too? > > Are there any limitations I should know before choosing a ARM device? > > Is there a vm for 64bit (aarch64)? > Hi Albrecht, I am also interested in this answer. In general, I am interested in IoT support for Smalltalk. The only thing I found aside from ARMv6 is this: https://github.com/OpenSmalltalk/opensmalltalk-vm/tree/Cog/build.linux32ARM… But I don't know what's the status of it. You may have more chances to get an answer with the vm list: <vm-dev(a)lists.squeakfoundation.org> Or maybe Pharo dev list. Cheers, -- Mariano Martinez Peck Email: marianopeck(a)gmail.com Twitter: @MartinezPeck LinkedIn: https://www.linkedin.com/in/mariano-mart%C3%ADnez-peck/

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How to catch and handle multiple exceptions
by Tim Mackinnon April 8, 2019

April 8, 2019

Hi - Iâm wondering what the best way for handling multiple exceptions is in Pharo? It seems like we just have on:do: (where on is a single exception?). However, I think Iâve noticed that you can concatenate exceptions - so DomainError, ZnHttpUnsuccessful - and then pass that to on: However, Iâm not clear on how we then elegantly process the exception if you want to do different things (which is often the case for unrelated exceptions). I am kind of superseded there isnât on:do:on:do: (although that seems quite ugly). So Iâm curious how you handle different exceptions without having some sort of case statement in the exception handler? Or do you wrap exceptions handlers over top of each other? Tim

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Iceberg for files other than code?
by Konrad Hinsen April 8, 2019

April 8, 2019

Hi everyone, Is it possible to read and modify files not containing Pharo code in a repository managed by Iceberg? I am thinking of reading the repository's README file, for example, or storing data files read by my code alongside the code itself. Konrad.

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can I do something like this with Double Dispatch
by Roelof Wobben April 8, 2019

April 8, 2019

Hello, Just thinking how to solve the bowling challenge from exercism. but I wonder if I can do something like this in the method that checks if I have the right object I was thinking about this : Result -- Strike -- Spare -- allOther then InÂ Strike something like this checkForBonus: number1 score2: number2 Â ^ number1 + number2 == 10 or am I thinking the totally wrong way to solve this? Roelof

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Advanced preferences for Pharo
by Cyril Ferlicot April 5, 2019

April 5, 2019

Hi, At PharoDays I presented how I am managing my preferences in Pharo in a more advanced way than using the preferences browser. (Because I do not want to be limited to the pre-defined settings) I am using a classic pharo project managed with Metacello that I load via a startup script to execute and add code. If some of you want to check how I am doing it, you can check the code at https://github.com/jecisc/pharo-scripts -- Cyril Ferlicot https://ferlicot.fr

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Auto/default selection in GLM
by Arturo Zambrano April 4, 2019

April 4, 2019

Hi all, I need to pre select an item in a list. Consider the following snipped, how do I tell the list the default selected item is, let say, Array? I could not find an example and tried different ways using transmissions with no luck | browser | browser := GLMTabulator new. browser title: 'test'; column: #classes; initialExtent: 200@300. browser transmit to: #classes; andShow: [ :pres | pres tree display: [ OrderedCollection with: Collection ]; children: [ :each | each subclasses]; allExpanded; format: [ :each | each name ]] . browser openOn: Collection TIA Arturo

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Difficulties setting up default image in XMonad
by Vanessa McHale April 4, 2019

April 4, 2019

Hi all, When I try to launch the latest Pharo image in XMonad, I run into the following: Pharo launch failure screenshot I couldn't copy the error text unfortunately so I have attached a screenshot instead. Any hints on what might be causing it? Is it due to my using a tiling window manager? Cheers, Vanessa McHale

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FFIExternalStructureReferenceHandle and pushing it to the stack
by Holger Freyther April 4, 2019

April 4, 2019

In addition to my mail from yesterday to vm-dev I want to share the following example to illustrate the problem. I have taken StructA and StructNested from the FFIExternalStructureReferenceHandle class comment and put it into Unclassified.st that is attached to this mail. I am also making a call to LibC's getpid and try to push StructNested to the stack. The ffiCall is failing before getpid is called (Bad argument to external function). The reproducer is: StructA new theNest anyCall. StructA has a ByteArray handle of the full struct. theNest returns an instance of StructNested with a FFIExternalStructureReferenceHandle. This makes sense as well. It can't be a copy of the ByteArray (or else updates would be invisible to the outer struct) and it can't be an ExternalAddress as StructA's handle might move in the Smalltalk heap. I am not entirely sure how this is should work but what do you think of: 1st) Extending ExternalStructure class comment to list FFIExternalStructureReferenceHandle as possible handle type? I think we would only describe the reality. 2nd) ThreadedFFIPlugin>>#ffiPushStructureContentsOf: should be aware of FFIExternalStructureReferenceHandle and know how to reach the handle. Or should there be something in the image converting this to a ByteArray when being pushed as value in a ffiCall? comments/ideas?

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is this valid smalltalk
by Roelof Wobben April 4, 2019

April 4, 2019

Hello, For a challenge of Exercism I need to check if some parenthes and brackets are balanced. so for example ()Â = true ([])Â = true but (])Â is not true because the bracket has no opening bracket. Now I wonder if I can premature end a #do:Â like this collection do: [:element | (condition with element) ifFalse: [^false]] in pseudo code is this a valid way to end the do ? or is there a better way ? Roelof

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FFI and when to convert the stack pointer (an Alien) into an ExternalAddress
by Holger Freyther April 4, 2019

April 4, 2019

I am toying with Ben's bindings to clang-c (C interface to the Clang C-indexer API). One of the main features of the C API is a way to visit the translation unit. This is implemented as a callback into Smalltalk with with "cursors" providing indirect access and simplified access to the node of the AST. The return result indicates how to continue the traversal (continue, stop, recurse). FFICallback signature: #( CXChildVisitResult ( CXCursor cursor, CXCursor parent, CXString client_data)) block: [ :cursor :parent :clientData | cursor spelling. <- booom but no crash aCXChildVisitResult value "@1" ]. "cursor" will be an Instance of CXCursor and is passed by value and the C struct size is >16 bytes (on Unix this is passed on the stack). The resulting CXCursor has a handle that is invalid to perform any call-out with. CXCursor getHandle FFIExternalStructureReferenceHandle handle: an Alien (isPointer = true, the stack ptr offset: 0 ExternalStructure defines valid types as ByteArray (the data) or ExternalAddress (the pointer). FFIExternalStructureReferenceHandle is missing there and I will create a separate thread/ticket about it. So somewhere from: FFICallback>>#valueWithContext:sp: ... FFICallbackArg>>#extractStructType: FFIExternalType>>#handle:at: FFIExternalStructureType>>#basicHandle:at: ee will need to convert the handle + offset (one based) to an ExternalAddress. Now the protocol of >>#handle:at: and >>#integerAt:, >>#pointerAt: indicate that we want to carry address+offset into late of the conversion. And I can't point my finger into where it should be done. I have created: Alien>>#referenceStructAt: byteOffset length: length ^self isPointer ifFalse: [super referenceStructAt: byteOffset length: length ] ifTrue: [ (ExternalAddress fromAddress: self addressField) + (byteOffset - 1)] This "fixes" it. But that is at the last point in the conversion. It shadows another problem as well. So in fact maybe changing: FFICallbackArgumentReader>>#extractPointerOfType: and >>#extractStructType: to read: ... pair := self nextBaseAddressForStructure: type. baseAddressToRead := ExternalAddress fromAddress: pair first address. <- modified offsetOfBaseAddress := pair second. ... is this the right way forward? We convert the stack to an ExternalAddress early on and use it. With the above change to FFICallbackArgumentReader the CXCursor from the stack will read as: CXCursor getHandle FFIExternalStructureReferenceHandle handle: ExternalAddress offset: 0 I am still not able to push this cursor to the stack. But that is for another mail. WDUT? holger

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