Archive for squeak

new website for Black Page Digital

Posted in Appsterdam, consulting, Context, GLASS, music, Naiad, Seaside, Smalltalk, Spoon with tags , , , , , , , , , , , , , , , , on 21 January 2016 by Craig Latta

I wrote a new website for Black Page Digital, my consultancy in Amsterdam and San Francisco. It features a running Squeak Smalltalk that you can use for livecoding. Please check it out, pass it on, and let me know what you think!pano

new Context active filesystem layout

Posted in Appsterdam, consulting, Context, Naiad, Smalltalk, Spoon with tags , , , , , , , , , , , , , on 22 December 2014 by Craig Latta

When you start the Context app, you start a webserver that provides a “console”. Viewed through a host web browser, the console describes what Context is, and enables control of the memories it knows about. The webserver also provides an active filesystem via WebDAV. This lets you interact with the console from a host terminal or text editor, in a manner reminiscent of a Unix procfs (content is generated live-on-read). Here’s a typical filesystem layout, and what you can do with it:

/
   README.html

   memories
      3EAD9A45-F65F-445F-89C1-4CA0A9D5C2F8
         session
            state
            performance
         classes
            Object
               metaclass
                  (etc.)
               methods
                  at:
                  (etc.)
               slots
                  all
                     (etc.)
                  inherited
                     (etc.)
                  local
                     (etc.)
               subclasses
                  (etc.)
         processes
            the idle process
               ProcessorScheduler class>>idleProcess
                  source
                  variables
                     thisContext
                     self
                     (etc.)
               [] in ProcessorScheduler class>>resume
               (etc.)
            (etc.)
         workspaces
            hello world
               source
               result
                  7

The README.html file is what the console displays initially. It has a directory sibling memories, containing a subdirectory for each memory the console knows about. Each memory is named by its UUID. In the session directory, there are files which give information about a memory. The state file looks like this:

# This memory is running. You can send it one of the following
# commands: snapshot, suspend, or stop. To do so, write this file with
# the desired command as the first word after this comment. Subsequent
# comments give other information about this memory, like host
# resource usage and virtual machine plugins loaded.

(type command here)

# host resource usage
#
# bytes used:        437,598
# bytes available: 1,328,467

# virtual machine plugins loaded
#
# FlowPlugin

In this way, a file in the active filesystem provides access to a read-eval-print loop (REPL). The user gives input to the console by writing the file; the console gives feedback to the user (including documentation) by generating appropriate content when the file is read.

The performance file looks like this:

# instructions per second: 382,184,269
# messages per second:      12,355,810

This gives general profiling information about the virtual machine.

The subdirectories of the classes directory correspond to the memory’s classes. Each one has subdirectories for its methods, subclasses, and metaclass. The methods directory has a file for each method of the class. This provides the ability to browse and change source code in the memory from a host text editor.

The processes directory has a subdirectory for each running process in the memory. Each process directory has a subdirectory for each context of that process. Each context directory has a REPL file for the source code of the context’s method, and a subdirectory for the context’s variables (including the context itself), each of which is an inspector in the form of a REPL file. In this way, much of the functionality of the traditional Smalltalk debugger is accessible from a host text editor.

Finally, the workspaces directory has subdirectories for multiple “workspaces”, where one may evaluate expressions and interact with their result objects. Each workspace has a source file, another REPL file which contains instructions, the expression to evaluate, and, on the next read after write, the textual form of the result. In addition, in a result directory, is a file named for the textual form of the result, containing a REPL inspector for that result object.

These tools are useful both for newcomers to live object systems who are more comfortable with a text editor than the Smalltalk GUI, and for those accessing systems running in the cloud, for which traditional GUI access might be awkward or prohibitive.

Smalltalk Reflections episode three is up

Posted in Appsterdam, consulting, Context, music, Smalltalk, Spoon with tags , , , , , , , , , , , , , , on 16 December 2014 by Craig Latta

Check it out!

debugging remote exceptions works

Posted in consulting, Context, Smalltalk, Spoon with tags , , , , , , on 20 November 2014 by Craig Latta
a debugger for a remote unhandled exception

a debugger for a remote unhandled exception

I have debugging working for remote unhandled exceptions. My motivating use case was debugging messages not understood by the Context console’s embedded web server. The console is a headless app. In development, I run it with a remote-messaging connection to a headful system. Now, when there is an unhandled exception (like a message not understood), the exception requests that the headful system open a debugger (as its default action).

Before opening the debugger, the headful system replaces the sender of the first relevant context on the headless system with the last relevant context on the headful system, hiding all the remote-messaging-related contexts in between. The picture above shows an example of this. On the headful system, I sent “zork” to an object on the headless system. The debugger shows a continuous context stack which spans the two systems. This all works with little special handling in the debugger because of the complete transparency of remote messaging. It doesn’t matter that the contexts and methods that the debugger is manipulating happen to be remote.

Context 3 beta 5 released

Posted in Context, Uncategorized with tags , , , , , , , on 4 March 2014 by Craig Latta

Hi, Context 3 beta 5 is released. I’ve still got a bunch of changes pending, for a 3b6 release to follow shortly. This release is just to fix some startup problems on Windows, Linux, and Mac OS. You can also find the Spoon VM changes separated out, in the second “Resources” folder.

What I’d like is for you to just start the app and tell me the results, along with your host platform. Thanks!

current design for Context’s virtual filesystem

Posted in consulting, Context, Naiad, Smalltalk, Spoon with tags , , , , , on 13 January 2014 by Craig Latta

I’m writing Context’s virtual filesystem support now. The directory structure looks like this:

--
root
   classes
      <each class>
         methods
            all
               <each method>
                  literals
                     <literal objects>
                  source
                  version
            inherited
               <inherited methods>
            local
               <locally-defined methods>
         slots
            all
               <each slot>
                  <instances ordered by slot>
                     references
                        <referring objects>
                     slots
                        <etc>
            inherited
               <etc>
            local
               <etc>
   processes
      <each process' suspended context>
         method
            instructions
            literals
               <literal objects>
         sender
            <etc>
   README.html
--

What do you think?

the initial Context webpage

Posted in consulting, Context, Naiad, Smalltalk, Spoon with tags , , , , , , , on 10 January 2014 by Craig Latta

Here’s what you currently see in a web browser when you start a Context system:

the initial Spoon webpage

the initial Spoon webpage

A Spoonful of Raspberry Pi

Posted in consulting, Naiad, Smalltalk, Spoon with tags , , , , , , , , , on 3 January 2014 by Craig Latta

Image

Spoon is up on the Raspberry Pi and exchanging remote messages with Spoon on my laptop. Morphic works, but it’s pretty slow, so I’ll be sticking with MVC for now (the Raspberry Pi is a 700MHz machine… I’m looking forward to Tim’s profiling work!). I’m writing a talk for FOSDEM in February called “A Spoonful of Raspberry Pi”. What should the Pi do? I’m eager to hear your suggestions!
Image

Another VM debugging trick: halting

Posted in consulting, Smalltalk, Spoon with tags , , , , on 31 December 2013 by Craig Latta

Just another little VM debugging trick I use… In one of my VM plugins I include a little C function called “breakHere”, which Smalltalk can call as a primitive. I put a breakpoint on it in the C debugger, and then have a convenient way to break in the C debugger from Smalltalk.

What services should the initial Context filesystem provide?

Posted in Context, Naiad, Smalltalk, Spoon with tags , , , , , , , , on 19 December 2013 by Craig Latta

The Context app is now mountable as a virtual (WebDAV) filesystem. What should it do? It has a file at the top level called “README.html”, which is obvious enough. What should the README describe? What would you want a newcomer to be able to do from their favorite text editor (or their favorite file-aware programming language)? Browse classes and methods? Resume and suspend object memories? Add and remove code modules? Please share your thoughts, keeping in mind that this is meant to be a minimal system (one can always add code modules to it later).

Image

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