Workspace & Globals

When you start the Beamtalk REPL, three global objects are automatically available: Transcript, Workspace, and Beamtalk. These are workspace-scoped singletons that provide logging, introspection, and class management.

Transcript — the shared log

Transcript is an actor that acts as a shared output log, similar to Smalltalk's Transcript window. Use it for debugging and tracing:

Transcript show: "Hello from Beamtalk"
Transcript show: "Step 1 complete"; cr
Transcript show: 42

show: accepts any value, converts it to a string, and appends it to an internal buffer. cr adds a newline. Both return self, so you can cascade them:

Transcript show: "Name: "; show: "Alice"; cr; show: "Done"

Retrieve recent output or clear the buffer:

Transcript recent   // returns the buffer contents as a list
Transcript clear     // empties the buffer

Pub/sub

Processes can subscribe to Transcript output in real-time:

Transcript subscribe    // subscribe the current process
Transcript unsubscribe  // unsubscribe

Subscribers receive messages whenever show: or cr is called. The Transcript automatically removes dead subscribers.

Workspace — introspection and binding management

Workspace is a value object (not an actor) that provides per-workspace introspection. Use it to explore loaded classes, manage actors, and register custom bindings.

Exploring classes

Workspace classes       // list all loaded user classes
Workspace testClasses   // list TestCase subclasses

Working with actors

Workspace actors              // list all live actors
Workspace actorsOf: Counter   // find actors of a specific class

Loading files

Workspace load: "path/to/MyClass.bt"  // compile and load a .bt file

Running tests

Workspace test               // run all test classes
Workspace test: MyTest       // run a specific test class

Custom bindings

Register your own workspace-level names:

Workspace bind: myConfig as: #Config   // register a binding
Workspace globals                       // see all bindings as a Dictionary
Workspace unbind: #Config              // remove a binding

The system prevents binding names that conflict with built-in globals (Transcript, Workspace, Beamtalk) or loaded class names.

Beamtalk — system reflection

Beamtalk provides VM-level reflection and the class registry:

Beamtalk version              // the Beamtalk version string
Beamtalk allClasses           // list all registered class names
Beamtalk classNamed: #Integer // look up a class by name
Beamtalk globals              // Dictionary of all system-level names

Getting help

Beamtalk help: Integer                       // show class documentation
Beamtalk help: Integer selector: #factorial  // show method documentation

Access from compiled code

The convenience bindings (Transcript, Workspace, Beamtalk) are injected by the workspace and are only available in the REPL and btscript contexts.

In compiled code (inside .bt class files), use the explicit class-variable form:

TranscriptStream current show: "Hello from compiled code"
WorkspaceInterface current classes
BeamtalkInterface current version

Each singleton class stores its instance in a current class variable, set during workspace bootstrap. This works everywhere — REPL, btscript, and compiled classes.

Summary

Transcript (actor — shared log):

Transcript show: value      → self (appends to buffer)
Transcript cr               → self (appends newline)
Transcript recent           → List (buffer contents)
Transcript clear            → nil (empties buffer)
Transcript subscribe        → self (subscribe to output)
Transcript unsubscribe      → self (unsubscribe)

Workspace (value object — workspace introspection):

Workspace classes            → List of loaded classes
Workspace testClasses        → List of TestCase subclasses
Workspace actors             → List of live actors
Workspace actorsOf: aClass   → List of actors of that class
Workspace load: path         → compile and load a .bt file
Workspace test               → run all test classes
Workspace test: testClass    → run a specific test class
Workspace bind: val as: name → register a binding
Workspace unbind: name       → remove a binding
Workspace globals            → Dictionary of all bindings

Beamtalk (value object — system reflection):

Beamtalk version                      → String
Beamtalk allClasses                   → List of class names
Beamtalk classNamed: name             → class object or nil
Beamtalk globals                      → Dictionary of system names
Beamtalk help: aClass                 → class documentation
Beamtalk help: aClass selector: sel   → method documentation

Exercises

1. Explore loaded classes. In the REPL, use Workspace classes to see all loaded classes. How many are there? Can you find Integer and String?

classes := Workspace classes
classes size    // shows the count
// Look for specific classes:
classes includes: Integer    // likely not — classes are names
// Use Beamtalk allClasses to find by name
Beamtalk allClasses

2. Transcript cascade. Use Transcript with cascade (;) to log your name, a newline, your favorite number, and another newline — all in one expression.

Transcript show: "Alice"; cr; show: 42; cr

3. Help system. Use Beamtalk help: Integer to explore the Integer class. Then use Beamtalk help: Integer selector: #factorial to see documentation for a specific method.

Beamtalk help: Integer                     // shows class docs
Beamtalk help: Integer selector: #factorial  // shows method docs

Next: Chapter 23 — Streams