System
System — OS environment, platform detection, and process info.
Provides class methods for accessing environment variables, detecting the operating system and architecture, and querying process-level information. All methods are class-side — System has no instances.
Examples
System getEnv: "HOME"
// => _
System getEnv: "MISSING"
// => nil
System osPlatform
// => _
System osFamily
// => _
System pid
// => _
System uniqueId
// => _
Methods
Class Methods
Read an environment variable by name. Returns nil if not set.
Examples
System getEnv: "HOME"
// => _
System getEnv: "NONEXISTENT_VAR_12345"
// => nil
Read an environment variable with a default fallback.
Returns the value if set, otherwise returns the default.
Examples
System getEnv: "NONEXISTENT_VAR_12345" default: "8080"
// => "8080"
Set an environment variable. Both arguments must be Strings.
Returns true on success. Raises #type_error for non-String arguments.
Examples
System setEnv: "BT_TEST_SET_ENV" value: "hello"
// => true
System getEnv: "BT_TEST_SET_ENV"
// => "hello"
Remove an environment variable. Argument must be a String.
Returns true on success. Raises #type_error for non-String argument.
Examples
System setEnv: "BT_TEST_UNSET_ENV" value: "temp"
// => true
System unsetEnv: "BT_TEST_UNSET_ENV"
// => true
System getEnv: "BT_TEST_UNSET_ENV"
// => nil
Return the OS platform name: "linux", "darwin", or "win32".
Examples
System osPlatform
// => _
Return the OS family: "unix" or "win32".
Examples
System osFamily
// => _
Return the system architecture string (e.g., "x86_64-pc-linux-gnu").
Examples
System architecture
// => _
Return the hostname of the current machine.
Examples
System hostname
// => _
Return the OTP/Erlang version string (e.g., "27").
Examples
System erlangVersion
// => _
Return the OS process ID as an Integer.
Examples
System pid
// => _
Return a unique positive monotonic integer.
Each call returns a value strictly greater than any previous call within this VM instance. Useful for generating unique IDs.
Examples
System uniqueId
// => _
Inherited Methods
From Object
Return the class of the receiver.
Examples
42 class // => Integer
"hello" class // => String
Test if the receiver is nil. Returns false for all objects except nil.
Examples
42 isNil // => false
nil isNil // => true
Test if the receiver is not nil. Returns true for all objects except nil.
Examples
42 notNil // => true
nil notNil // => false
If the receiver is nil, evaluate nilBlock. Otherwise return self.
Examples
42 ifNil: [0] // => 42
nil ifNil: [0] // => 0
If the receiver is not nil, evaluate notNilBlock with self.
Examples
42 ifNotNil: [:v | v + 1] // => 43
nil ifNotNil: [:v | v + 1] // => nil
If nil, evaluate nilBlock; otherwise evaluate notNilBlock with self.
Examples
42 ifNil: [0] ifNotNil: [:v | v + 1] // => 43
nil ifNil: [0] ifNotNil: [:v | v + 1] // => 0
If not nil, evaluate notNilBlock with self; otherwise evaluate nilBlock.
Examples
42 ifNotNil: [:v | v + 1] ifNil: [0] // => 43
nil ifNotNil: [:v | v + 1] ifNil: [0] // => 0
Return a developer-readable string representation.
Default implementation returns "a ClassName". Subclasses such as
Integer, String, and List override this to return richer output.
Examples
42 printString // => "42"
Return a user-facing string representation for display purposes.
Default implementation delegates to printString. Subclasses such as
String and Symbol override this to return a more readable form without
developer annotations (e.g. no surrounding quotes or # prefix).
Examples
42 displayString // => "42"
Inspect the receiver.
Examples
42 inspect // => "42"
Return the receiver itself. Useful for cascading side effects.
Examples
42 yourself // => 42
Return a hash value for the receiver.
Examples
42 hash
Test if the receiver responds to the given selector.
Examples
42 respondsTo: #abs // => true
Return the names of fields.
Examples
42 fieldNames // => #()
Return the value of the named field.
Examples
object fieldAt: #name
Set the value of the named field (returns new state).
Examples
object fieldAt: #name put: "Alice"
Send a unary message dynamically.
Examples
42 perform: #abs // => 42
Send a message dynamically with arguments.
Examples
3 perform: #max: withArguments: #(5) // => 5
Raise an error indicating this method must be overridden by a subclass.
Examples
self subclassResponsibility
Raise an error indicating this method has not yet been implemented.
Use this for work-in-progress stubs. Distinct from subclassResponsibility,
which signals an interface contract violation.
Examples
self notImplemented
Send aValue to the current transcript without a trailing newline.
Nil-safe: does nothing when no transcript is set (batch compile, tests).
Examples
42 show: "value: "
Send aValue to the current transcript followed by a newline.
Nil-safe: does nothing when no transcript is set (batch compile, tests).
Examples
42 showCr: "hello world"
Test if the receiver is an instance of aClass or any of its subclasses.
Examples
42 isKindOf: Integer // => true
42 isKindOf: Object // => true
#foo isKindOf: Symbol // => true
#foo isKindOf: String // => false
Raise an error with the given message.
Examples
self error: "something went wrong"
From ProtoObject
Test value equality (Erlang ==).
Examples
42 == 42 // => true
"abc" == "abc" // => true
Test value inequality (negation of ==).
Examples
1 /= 2 // => true
42 /= 42 // => false
Return the class of the receiver.
Examples
42 class // => Integer
"hello" class // => String
Handle messages the receiver does not understand. Override for custom dispatch.
Examples
42 unknownMessage // => ERROR: does_not_understand
Send a message dynamically with an arguments list.
Examples
42 perform: #abs withArguments: #() // => 42
Execute a class method in the caller's process, bypassing gen_server dispatch.
The caller takes responsibility for knowing the method does not mutate class state. Useful for long-running class methods that would otherwise block the class object's gen_server.
Limitations: only resolves methods defined directly on the target class
module (does not walk the superclass chain). Class variables and self
are not available to the method (nil and #{} are passed).
Examples
MyClass performLocally: #run:ctx: withArguments: #(input, ctx)
Send a message dynamically with an arguments list and explicit timeout.
The timeout (in milliseconds or #infinity) applies to the gen_server:call
when the receiver is an actor. For value types, timeout is ignored.
Examples
actor perform: #query withArguments: #(sql) timeout: 30000