Object abstract superclass of all objects
Object is the root class of all other classes. All objects are indirect instances of class Object.
We call "receiver" the object the message is sent to: receiver.method(argument).
Superclass: nil (Not the Nil class, but the nil instance).
See also: Class, Intro-to-Objects, Classes
Class Membership
class
Answer the class of the receiver.
5.class;
respondsTo(selector)
Answer a Boolean whether the receiver understands the message selector. selector must be a Symbol.
5.respondsTo('+');
isKindOf(aClass)
Answer a Boolean indicationg whether the receiver is a direct or indirect instance of aClass. Use of this message in code must be questioned, because it often indicates a missed opportunity to exploit object polymorphism.
5.isKindOf(Magnitude);
isMemberOf(aClass)
Answer a Boolean whether the receiver is a direct instance of aClass. Use of this message in code is almost always a design mistake.
5.isMemberOf(Magnitude);
Accessing
size
Different classes interpret this message differently. Object always returns 0.
Copying
copy
Make a copy of the receiver. The implementation of this message depends on the object's class. In class Object, copy calls shallowCopy.
shallowCopy
Makes a copy of the object. The copy's named and indexed instance variables refer to the same objects as the receiver.
deepCopy
Recursively copies the object and all of the objects contained in the instance variables, and so on down the structure. This method works with cyclic graphs.
copyImmutable
If object is immutable then return a shallow copy, else return receiver.
Conversion
To convert an object of a certain Class into a similar, Object provides a number of methods.
as(class)
Returns a similar new Object of a different class.
[1, 2, 3].as(Set);
Pwhite(0.0, 1.0, 10).as(Set);
asArray
Returns an Array with the receiver, unless it is an Array already.
[1, 2, 3].asArray;
5.asArray;
asCompileString
Returns a String that can be interpreted to reconstruct a copy of the receiver.
For the complementary method, see String interpret .
a = { 10.do { 10.postln } };
a.asCompileString.postcs;
a.postcs;
Archiving
Object implements methods for writing and retrieving objects from disk. Note that you cannot archive instances of Thread and its subclasses (i.e. Routine), or open Functions (i.e. a Function which refers to variables from outside its own scope).
writeArchive(pathname)
Write an object to disk as a text archive. pathname is a String containing the resulting file's path.
*readArchive(pathname)
Read in an object from a text archive. pathname is a String containing the archive file's path.
a = Array.fill(100, { 100.0.rand });
a.writeArchive(PathName.tmp ++ "myArray");
b = Object.readArchive(PathName.tmp ++ "myArray");
a == b // true
/////////
// closed Function
(
f = { 1 + 2 };
f.writeArchive(PathName.tmp ++ "myFunc"); // succeeds
)
// open Function
(
var num;
num = 2;
f = { num + 2 };
f.writeArchive(PathName.tmp ++ "myFunc"); // fails
)
Equality and Identity
== anotherObject
equality: Answer whether the receiver equals anotherObject. The definition of equality depends on the class of the receiver. The default implementation in Object is to answer if the two objects are identical (see below).
5.0 == 5; // true
5.0 === 5; // false
a = [1, 2, 3]; b = [1, 2, 3];
a == b; // equal
a === b; // not identical
=== anotherObject
identity: Answer whether the receiver is the exact same object as anotherObject.
5.0 === 5; // false
!= anotherObject
non-equality: Answer whether the receiver does not equal anotherObject. The default implementation in Object is to answer if the two objects are not identical (see below).
fuzzyEqual(that, precision)
Retruns the degree of equality between two objects with regard to a given precision. Objects to compare must support max, substraction and division.
5.0.fuzzyEqual(5.0, 0.5); // 1 - full equality
5.25.fuzzyEqual(5.0, 0.5); // 0.5 - 50 % equality
5.9.fuzzyEqual(5.0, 0.5); // 0 - no equality
compareObject(that, instVarNames)
Tests if two Objects are the same in a certain respect: It returns true if instVarNames are equal in both. If none are given, all instance variables are tested.
a = Pseq([1, 2, 3], inf); b = Pseq([100, 200, 300], inf);
a.compareObject(b, [\repeats]); // true
a.compareObject(b, [\list]); // false
hash
Answer a code used to index into a hash table. This is used by Dictionary and Set and their subclasses to implement fast object lookup. Objects which are equal == should have the same hash values. Whenever == is overridden in a class, hash should be overridden as well.
identityHash
Answer a code used to index into a hash table. This method is implemented by a primitive and is not overridden. Objects which are identical === should have the same hash values.
Testing
isNil
Answer a Boolean indicating whether the receiver is nil.
notNil
Answer a Boolean indicating whether the receiver is not nil.
isNumber
Answer a Boolean indicating whether the receiver is an instance of Number.
isInteger
Answer a Boolean indicating whether the receiver is an instance of Integer.
isFloat
Answer a Boolean indicating whether the receiver is an instance of Float.
? anObject
If the receiver is nil then answer anObject, otherwise answer the receiver.
?? aFunction
If the receiver is nil, evaluate the Function and return the result.
pointsTo(obj)
Returns true if receiver has a direct reference to obj.
a = 9;
b = [1, a, 6, 8];
c = [1, b, 5];
c.pointsTo(b); // true
c.pointsTo(a); // false
mutable
Returns true if receiver is mutable.
a = #[1, 2, 3]; b = [1, 2, 3];
a.mutable; // false
b.mutable; // true
frozen
Returns true if receiver is frozen.
switch(cases)
Object implements a switch method which allows for conditional evaluation with multiple cases. These are implemented as pairs of test objects (tested using if this == test.value) and corresponding functions to be evaluated if true. In order for switch to be inlined (and thus be as efficient as nested if statements) the matching values must be literal Integers, Floats, Chars, Symbols and the functions must have no variables or arguments.
(
var x, z;
z = [0, 1, 1.1, 1.3, 1.5, 2];
switch (z.choose.postln,
1, { \no },
1.1, { \wrong },
1.3, { \wrong },
1.5, { \wrong },
2, { \wrong },
0, { \true }
).postln;
)
or:
(
var x, z;
z = [0, 1, 1.1, 1.3, 1.5, 2];
x = switch (z.choose)
{1} { \no }
{1.1} { \wrong }
{1.3} { \wrong }
{1.5} { \wrong }
{2} { \wrong }
{0} { \true };
x.postln;
)
Messaging
Instead of directly sending a method to an object, a method may be invoked given a method selector only (a Symbol). The other arguments may be provided by passing them directly, from an environment. If it si not known whether the receiver implements the metod, tryPerform only sends if it does, and superPerform invokes the method of the superclass.
perform(selector ... args)
The selector argument must be a Symbol. Sends the method named by the selector with the given arguments to the receiver.
performList(selector, [args])
The selector argument must be a Symbol. Sends the method named by the selector with the given arguments to the receiver. If the last argument is a List or an Array, then its elements are unpacked and passed as arguments.
a = { |a, b, c| postf("% plus % plus % is %\n", a, b, c, a + b + c); "" };
a.performList(\value, [1, 2, 3]);
performMsg([args])
The argument must be a List or Array whose first element is a Symbol representing a method selector. The remaining elements are unpacked and passed as arguments to the method named by the selector.
a = { |a, b, c| postf("% plus % plus % is %\n", a, b, c, a + b + c); "" };
a.performMsg([\value, 1, 2, 3]);
performWithEnvir(selector, envir)
selector: A Symbol representing a method selector.
envir: The remaining arguments derived from the environment and passed as arguments to the method named by the selector.
a = { |a, b, c| postf("% plus % plus % is %\n", a, b, c, a + b + c); "" };
a.performWithEnvir(\value, (a: 1, c: 3, d: 4, b: 2));
performKeyValuePairs(selector, pairs)
selector: A Symbol representing a method selector.
pairs: Array or List with key-value pairs.
a = { |a, b, c| postf("% plus % plus % is %\n", a, b, c, a + b + c); "" };
a.performKeyValuePairs(\value, [\a, 1, \b, 2, \c, 3, \d, 4]);
tryPerform(selector ... args)
Like 'perform', but tryPerform passes the method to the receiver only if the receiver understands the method name. If the receiver doesn't implement that method, the result is nil. Note that this does not catch errors like 'try' does (see Exception). If the receiver does have a matching method but that method throws an error, execution will halt. But, 'tryPerform' is faster than 'try'.
(a: 1, b: 2, c: 3).tryPerform(\keysValuesDo, { |key, value| [key, value].postln });
// Array does not understand keysValuesDo -- result is nil
[1, 2, 3].tryPerform(\keysValuesDo, { |key, value| [key, value].postln });
// Error occurs within keysValuesDo -- error is thrown back to halt execution
(a: 1, b: 2, c: 3).tryPerform(\keysValuesDo, { |key, value| [key, value].flippityblargh });
superPerform(selector, ... args)
Like perform, superPerform calls a method, however it calls the method on the superclass.
selector: A Symbol representing a method selector.
args: Method arguments.
superPerformList([args])
Like performList, superPerformList calls a method, however it calls the method on the superclass.
selector: A Symbol representing a method selector.
args: Method arguments. If the last argument is a List or an Array, then its elements are unpacked and passed as arguments.
multiChannelPerform(selector ... args)
selector: A Symbol representing a method selector.
args: Method arguments, which if they contain an array, will call the method multiple times for each sub-element.
a = { |a, b, c| format("% plus % times % is %", a, b, c, a + b * c).quote; };
a.multiChannelPerform(\value, [1, 10, 100, 1000], [2, 7, 9], [3, 7]);
Unique Methods
Method definitions not yet implemented may be added to an Object instance.
addUniqueMethod(selector, function)
Add a unique method.
a = 5;
a.addUniqueMethod(\sayHello, { |to| "hello " ++ to ++ ", I am 5" });
a.sayHello;
removeUniqueMethod(selector)
Remove a unique method.
a.removeUniqueMethod(\sayHello);
a.sayHello;
removeUniqueMethods
Remove all unique methods of an Object.
Dependancy
addDependant(aDependant)
Add aDependant to the receiver's list of dependants.
removeDependant(aDependant)
Remove aDependant from the receiver's list of dependants.
dependants
Returns an IdentitySet of all dependants of the receiver.
changed(theChanger)
Notify the receiver's dependants that the receiver has changed. The object making the change should be passed as theChanger.
update(theChanged, theChanger)
An object upon which the receiver depends has changed. theChanged is the object that changed and theChanger is the object that made the change.
release
Remove all dependants of the receiver. Any object that has had dependants added must be released in order for it or its dependants to get garbage collected.
Error Support
Object implements a number of methods which throw instances of Error. A number of methods (e.g. doesNotUnderstand) are 'private' and do not normally need to be called directly in user code. Others, such as those documented below can be useful for purposes such as object oriented design (e.g. to define an abstract interface which will be implemented in subclasses) and deprecation of methods. The reserved keyword thisMethod can be used to refer to the enclosing method. See also Method and Function (for exception handling).
throw
Throws the receiver as an Exception, which may or may not be caught and handled by any enclosing Function.
subclassResponsibility(method)
Throws a SubclassResponsibilityError. Use this to indicate that this method should be defined in all subclasses of the receiver.
someMethod {
this.subclassResponsibility(thisMethod);
}
shouldNotImplement(method)
Throws a ShouldNotImplementError. Use this to indicate that this inherited method should not be defined or used in the receiver.
deprecated(method, alternateMethod)
Throws a DeprecatedError. Use this to indicate that the enclosing method has been replaced by a better one (possibly in another class), and that it will likely be removed in the future. Unlike other errors, DeprecatedError only halts execution if Error.debug == true. In all cases it posts a warning indicating that the method is deprecated and what is the recommended alternative.
foo {
this.deprecated(thisMethod, ThisOrSomeOtherObject.findMethod(\foo);
... // execution of this method will continue unless Error.debug == true
}
Printing and Introspection
post
Print a string representation of the receiver to the post window.
"hello".post; "hello".post; "";
postln
Print a string representation of the receiver followed by a newline.
"hello".postln; "hello".postln; "";
postc
Print a string representation of the receiver preceded by comments.
"hello".postc; "hello".postc; "";
postcln
Print a string representation of the receiver preceded by comments, followed by a newline.
"hello".postcln; "hello".postcln; "";
postcs
Print the compile string representation of the receiver, followed by a newline.
"hello".postcs; "hello".postcs; "";
dump
Print a detailed low level representation of the receiver to the post window.
System Information
gcInfo
Posts garbage collector information in a table format.
flips: the number of times the GC "flipped", i.e. when it finished incremental scanning of all reachable objects
collects: the number of partial collections performed
nalloc: total number of allocations
alloc: total allocation in bytes
grey: the number of "grey" objects, i.e. objects that point to reachable objects and are not determined to be (un)reachable yet
Then for each size class: numer of black, white and free objects, total number of objects and the total set size.
flips 241 collects 689096 nalloc 40173511 alloc 322496998 grey 346541
0 bwf t sz: 882 0 368573 369455 2955640
1 bwf t sz: 6197 122 5702377 5708696 91339136
2 bwf t sz: 947 4 1500009 1500960 48030720
3 bwf t sz: 8056 65201 301800 375057 24003648
4 bwf t sz: 4047 145 3457 7649 979072
5 bwf t sz: 422 1 431 854 218624
6 bwf t sz: 124 2 72 198 101376
7 bwf t sz: 153504 1 0 153505 157189120
8 bwf t sz: 22 0 0 22 45056
9 bwf t sz: 5 0 0 5 20480
10 bwf t sz: 5 0 0 5 40960
12 bwf t sz: 2 0 0 2 65536
13 bwf t sz: 1 0 0 rss="p7"> update(theChanged, theChanger)
An object upon which the receiver depends has changed. theChanged is the object that changed and theChanger is the object that made the change.
release
Remove all dependants of the receiver. Any object that has had dependants added must be released in order for it or its dependants to get garbage collected.
Error Support
Object implements a number of methods which throw instances of Error. A number of methods (e.g. doesNotUnderstand) are 'private' and do not normally need to be called directly in user code. Others, such as those documented below can be useful for purposes such as object oriented design (e.g. to define an abstract interface which will be implemented in subclasses) and deprecation of methods. The reserved keyword thisMethod can be used to refer to the enclosing method. See also Method and Function (for exception handling).
throw
Throws the receiver as an Exception, which may or may not be caught and handled by any enclosing Function.
subclassResponsibility(method)
Throws a SubclassResponsibilityError. Use this to indicate that this method should be defined in all subclasses of the receiver.
someMethod {
this.subclassResponsibility(thisMethod);
}
shouldNotImplement(method)
Throws a ShouldNotImplementError. Use this to indicate that this inherited method should not be defined or used in the receiver.
deprecated(method, alternateMethod)
Throws a DeprecatedError. Use this to indicate that the enclosing method has been replaced by a better one (possibly in another class), and that it will likely be removed in the future. Unlike other errors, DeprecatedError only halts execution if Error.debug == true. In all cases it posts a warning indicating that the method is deprecated and what is the recommended alternative.
foo {
this.deprecated(thisMethod, ThisOrSomeOtherObject.findMethod(\foo);
... // execution of this method will continue unless Error.debug == true
}
Printing and Introspection
post
Print a string representation of the receiver to the post window.
"hello".post; "hello".post; "";
postln
Print a string representation of the receiver followed by a newline.
"hello".postln; "hello".postln; "";
postc
Print a string representation of the receiver preceded by comments.
"hello".postc; "hello".postc; "";
postcln
Print a string representation of the receiver preceded by comments, followed by a newline.
"hello".postcln; "hello".postcln; "";
postcs
Print the compile string representation of the receiver, followed by a newline.
"hello".postcs; "hello".postcs; "";
dump
Print a detailed low level representation of the receiver to the post window.
System Information
gcInfo
Posts garbage collector information in a table format.
flips: the number of times the GC "flipped", i.e. when it finished incremental scanning of all reachable objects
collects: the number of partial collections performed
nalloc: