Object

The root of the class hierarchy. Every class in Maggie ultimately inherits from Object. Provides identity comparison, nil testing, class access, copying, error handling, and a default printString.

Test

3 yourself >>> 3
nil isNil >>> true
3 isNil >>> false
3 notNil >>> true

Class Methods

primitives

class allClasses

Return an array of all classes in the system.

class allClassesSorted

class allInstVarNames

class allMethodNames

class basicNew

class categoryOf:

class class

class classMethodCategories

class classMethodSourceFor:

class compileAndInstall:

class compileAndInstallClassMethod:

class docString

class help

class help:

class instVarNames

class methodCategories

class methodDocFor:

class methodSourceFor:

class methodsInCategory:

class name

class new

Create a new instance of this class.

class printString

class superclass

class superclassName

Instance Methods

primitives

become:

becomeForward:

className

docString

hash

Return a hash value for the receiver.

help

ifNil:

If the receiver is nil, evaluate block; otherwise return self.

ifNil:ifNotNil:

Evaluate nilBlock if nil, notNilBlock with self otherwise.

ifNotNil:

If the receiver is not nil, evaluate block with self; otherwise return nil.

instVarAt:

instVarAt:put:

instVarSize

isFailure

isForwarded

isSuccess

perform:

Send a message with the given selector to the receiver.

perform:with:

Send a one-argument message to the receiver.

primAddDependent:

Add a dependent to the receiver's notification list.

primAsCueValue

primClass

primDependents

Return an Array of the receiver's dependents.

primError:

primIdentical:

primIsKindOf:

primReleaseDependents

Remove all dependents from the receiver.

primRemoveDependent:

Remove a dependent from the receiver's notification list.

primShallowCopy

uncategorized

Return true if the receiver and other are equal. The default implementation delegates to identity (==). Subclasses may override this to provide value equality.

Test

3 = 3 >>> true
3 = 4 >>> false
'hello' = 'hello' >>> true

Return true if the receiver and other are the exact same object (identity comparison). Two objects that are == always have the same identity; value equality uses = instead.

Test

3 == 3 >>> true
3 == 4 >>> false
nil == nil >>> true

addDependent:

Register anObject as a dependent of the receiver. When the receiver sends changed or changed:, anObject will receive update: with the change aspect. Returns the dependent.

Test

model := Object new. dep := Object new.
model addDependent: dep.
model dependents size >>> 1

asCueValue

Project this object's instance variables into a CUE value. Returns a CueValue whose fields are the ivar names with their current values. Scalars (numbers, strings, booleans) project as CUE scalars. Objects with named ivars project as CUE structs.

Test

42 asCueValue kind >>> 'int'
'hello' asCueValue kind >>> 'string'

changed

Notify all dependents that the receiver has changed, with nil as the aspect.

changed:

Notify all dependents that the receiver has changed, passing anAspect (typically a symbol) to each dependent's update: method.

Test

model := Object new. dep := Object new.
model addDependent: dep.
model dependents size >>> 1

class

Return the class of the receiver as a first-class class value.

Test

3 class name >>> #SmallInteger
true class name >>> #True
nil class name >>> #UndefinedObject

dependents

Return an Array of the receiver's dependents. Returns an empty Array if there are no dependents.

Test

Object new dependents size >>> 0

doesNotUnderstand:

Called by the VM when a message is sent to an object that does not understand it. Signals an error with the unrecognized selector name.

Example

"Typically not called directly -- triggered by the VM"
3 frobnicate   "=> error: Message not understood: frobnicate"

error:

Signal an error with the given message string.

Example

self error: 'something went wrong'

isAssignment

isBlock

isCascade

isKindOf:

Return true if the receiver is an instance of aClass or one of its subclasses. Uses class identity comparison via the primitive.

Example

3 isKindOf: SmallInteger

isLiteral

isMessageSend

isNil

Return false. Object is not nil; only UndefinedObject (the class of nil) overrides this to return true.

Test

3 isNil >>> false
'hello' isNil >>> false
nil isNil >>> true

isReturn

Return false. Used internally by the compiler to test AST node types.

isVariable

Return false. Used internally by the compiler to test AST node types.

notNil

Return true if the receiver is not nil.

Test

3 notNil >>> true
nil notNil >>> false

printString

Return a human-readable representation.

release

Remove all dependents from the receiver. Use this when an object is being discarded to avoid stale references.

removeDependent:

Remove anObject from the receiver's dependents list. Returns the dependent. No error if anObject was not a dependent.

Test

model := Object new. dep := Object new.
model addDependent: dep.
model removeDependent: dep.
model dependents size >>> 0

respondsTo:

Return true if the receiver's class (or any superclass) implements the given selector.

Test

3 respondsTo: #printString >>> true
3 respondsTo: #frobnicate >>> false

shallowCopy

Return a shallow copy of the receiver. Instance variables are shared (not deeply copied) between the original and the copy.

Example

| original <Array> copy <Array> |
original := Array new: 3.
copy := original shallowCopy.
copy == original   "false -- different object"

update:

Called when a dependent object receives a change notification. Override this in subclasses to respond to model changes. The default implementation does nothing.

yourself

Return the receiver. Useful at the end of a cascade to yield the original object rather than the last message result.

Test

3 yourself >>> 3
'hello' yourself >>> 'hello'

Return true if the receiver and other are NOT equal. This is the negation of =.

Test

3 ~= 4 >>> true
3 ~= 3 >>> false

Return true if the receiver and other are NOT the same object. This is the negation of ==.

Test

3 ~~ 4 >>> true
3 ~~ 3 >>> false