On 03-04-2017, at 2:59 PM, Paul DeBruicker pdebruic@gmail.com wrote:

The blue book http://stephane.ducasse.free.fr/FreeBooks/BlueBook/Bluebook.pdf

And don’t forget the ‘middle path’ describing the original Squeak VM at http://www.rowledge.org/resources/tim%27s-Home-page/Squeak/OE-Tour.pdf It’s a somewhat simpler an artefact to understand than the full Cog VM, so makes a better place to begin.

tim -- tim Rowledge; tim@rowledge.org; http://www.rowledge.org/tim Strange OpCodes: EOS: Erase Operating System

That too: https://clementbera.wordpress.com/2014/06/02/squeak-pharo-vm-documentation-l...

On Mon, Apr 3, 2017 at 6:30 PM, Ben Coman btc@openinworld.com wrote:

On Tue, Apr 4, 2017 at 5:59 AM, Paul DeBruicker pdebruic@gmail.com wrote:

...

The blue book http://stephane.ducasse.free.fr/FreeBooks/BlueBook/Bluebook.pdf

and all the info on this blog should get you started

http://www.mirandabanda.org/cogblog/about-cog/

michel sangala wrote

...

Good morning, i want to know all about pharo'VM, books and notes, i also want to know differences between pharo'VM and JavaVM, thanks a lot

At its most concise:

• #become:
• resumable exceptions
• message passing
• its just an execution engine

The links below expand on these, except the last which I'll expand on briefly.

IIUC, the JVM class libraries are often considered part of the VM. With Smalltalk, the class libraries are part of *your* Image, written in Smalltalk (you have direct access to understanding and debugging them in the context of your running application). The Pharo VM provides only:

• bytecode interpreter
• JIT bytecode to machine code compilation
• memory allocation
• primitives hiding platform differences
• primitives accelerating speed sensitive activities

https://gbracha.blogspot.com.au/2009/07/miracle-of-become.html

http://stackoverflow.com/questions/18231382/java-equivalent-of-smalltalks- become

http://forum.world.st/Debugging-in-Production- Servers-tp4756136p4756337.html

http://scg.unibe.ch/archive/papers/Vran12a.pdf

http://swing.fit.cvut.cz/projects/stx/doc/online/english/programming/ stForJavaGuys.html

https://pdfs.semanticscholar.org/a0e2/5003010f1e2e3af958208ac9a540c8 c7bc4b.pdf

http://stackoverflow.com/questions/3102695/what-are- the-key-differences-between-oo-in-smalltalk-and-java

http://stackoverflow.com/questions/5638052/is-it-really-all-about-message- passing-in-smalltalk/5638259

http://softwareengineering.stackexchange.com/questions/ 140602/what-is-message-passing-in-oo

https://www.quora.com/What-is-the-difference-between- message-passing-versus-calling-a-function-method-invocation

btw, note that the Pharo VM is a branding of the OpenSmalltalk-VM, https://github.com/OpenSmalltalk/opensmalltalk-vm which is the original Squeak-VM renamed, since there are now several downstream consumers: Pharo, Squeak, Cuis & Newspeak.

cheers -ben

P.S. just an aside for anyone unfamiliar with reading Smalltalk syntax... http://www2.ing.unipi.it/~a009435/issw/extra/readingSmalltalk.pdf

Hi Ben,

On Mon, Apr 3, 2017 at 6:30 PM, Ben Coman btc@openinworld.com wrote:

On Tue, Apr 4, 2017 at 5:59 AM, Paul DeBruicker pdebruic@gmail.com wrote:

...

The blue book http://stephane.ducasse.free.fr/FreeBooks/BlueBook/Bluebook.pdf

and all the info on this blog should get you started

http://www.mirandabanda.org/cogblog/about-cog/

michel sangala wrote

...

Good morning, i want to know all about pharo'VM, books and notes, i also want to know differences between pharo'VM and JavaVM, thanks a lot

At its most concise:

• #become:
• resumable exceptions
• message passing
• its just an execution engine

I see three important things missing, contexts, self-definition and doesNotUnderstand:.

Contexts are really important to Smalltalk-80 Smalltalks (true Smalltalks). Smalltalk provides access to the current activation record from the language. Hence the exception system is largely above the VM. The only thing that needs to be in the VM is unwind-protect. Everything else (exception search, handler activation) can be done by walking the linked list of method activations starting from thisContext. Hence the debugger is written entirely in Salltalk and execution can be simulated above the VM by sending messages to contexts to ask them to interpret their methods' bytecodes. Hence processes can be serialized, exchanged between images, etc.

Self-definition (why the VM is just an execution engine): All the objects that comprise a Smalltalk program are themselves defined by Smalltalk classes. So classes are general instances of Class or Metaclass (instances of specific metaclasses that inherit from either Class or Metaclass). Methods are instances of CompiledMethod. Activation records are instances of class Context (MethodContext or BlockContext in older versions). Hence the compiler is written in Smalltalk and does not live in the VM.

doesNotUnderstand:, a key part of message passing. When a message is sent to an object and that object's class, nor any superclass of the class implements a method with the message's selector, the VM reifies the message as an instance of Message (holding selector and arguments) and sends doesNotUnderstand: to the object with the message as an argument. Hence Smalltalk provides transparent proxies that can catch messages and forward them. Implement a class that doesn't inherit from Object and implements doesNotUnderstand: and its instances catch any and all messages sent to them.

The links below expand on these, except the last which I'll expand on briefly.

IIUC, the JVM class libraries are often considered part of the VM. With Smalltalk, the class libraries are part of *your* Image, written in Smalltalk (you have direct access to understanding and debugging them in the context of your running application). The Pharo VM provides only:

• bytecode interpreter
• JIT bytecode to machine code compilation
• memory allocation
• primitives hiding platform differences
• primitives accelerating speed sensitive activities

https://gbracha.blogspot.com.au/2009/07/miracle-of-become.html

http://stackoverflow.com/questions/18231382/java-equivalent-of-smalltalks- become

http://forum.world.st/Debugging-in-Production- Servers-tp4756136p4756337.html

http://scg.unibe.ch/archive/papers/Vran12a.pdf

http://swing.fit.cvut.cz/projects/stx/doc/online/english/programming/ stForJavaGuys.html

https://pdfs.semanticscholar.org/a0e2/5003010f1e2e3af958208ac9a540c8 c7bc4b.pdf

http://stackoverflow.com/questions/3102695/what-are- the-key-differences-between-oo-in-smalltalk-and-java

http://stackoverflow.com/questions/5638052/is-it-really-all-about-message- passing-in-smalltalk/5638259

http://softwareengineering.stackexchange.com/questions/ 140602/what-is-message-passing-in-oo

https://www.quora.com/What-is-the-difference-between- message-passing-versus-calling-a-function-method-invocation

btw, note that the Pharo VM is a branding of the OpenSmalltalk-VM, https://github.com/OpenSmalltalk/opensmalltalk-vm which is the original Squeak-VM renamed, since there are now several downstream consumers: Pharo, Squeak, Cuis & Newspeak.

cheers -ben

P.S. just an aside for anyone unfamiliar with reading Smalltalk syntax... http://www2.ing.unipi.it/~a009435/issw/extra/readingSmalltalk.pdf