| Perbandingan -- programming languages (object-oriented programming)This Perbandingan -- programming languages compares how object-oriented programming languages such as C++, Python, Perl, Java, Object Pascal and others manipulate data structures.
Object construction and destruction | construction | destruction |
|---|
| ABAP Objects | data variable type ref to class .
create object variable «exporting parameter = argument[1]». | [2][3] | | C++ (STL) | class variable«(parameters)»; or
class *variable = new class«(parameters)»; | delete pointer; | | C# | class variable = new class(parameters); | variable.Dispose();[3] | | Java | variable.dispose();[3] | | D | delete variable; | | Objective-C (Cocoa) | class *variable = [[class alloc ] init]; or
class *variable = [[class alloc ] initWithFoo:parameter «bar:parameter ...»]; | [variable release]; | | Python | variable = class(parameters) | del variable[3] (Normally not needed) | | Visual Basic .NET | Dim variable As New class(parameters) | variable.Dispose()[3] | | Eiffel | create variable or
create «{TYPE}» variable.make_foo «(parameters)» or
variable := create {TYPE} or
variable := create {TYPE}.make_foo «(parameters)» | [3] | | PHP | $variable = new class(parameters); | unset($variable); | | Perl 5 | «my »$variable = class->new«(parameters)»; | undef($variable); | | Perl 6 | «my »$variable = class.new«(parameters)»; | $variable.undefine; | | Ruby | variable = class.new«(parameters)» | [3] | | Windows PowerShell | $variable = New-Object «-TypeName» class ««-ArgumentList» parameters» | Remove-Variable «-Name» variable | | OCaml | let variable = new class «parameters» or
let variable = object members end[4] | [3] | | F# | let variable = «new »class(«parameters») | | Smalltalk | "The class is an Object.
Just send a message to a class, usually #new or #new:, and many others, for example:"
Pointy x: 10 y: 20.
Array with: -1 with: 3 with: 2. | | | JavaScript | var variable = new class«(parameters)» or
var variable = { «key1: value1«, key2: value2 ...»»} | [3] | | Object Pascal / Delphi | ClassVar := ClassType.ConstructorName(parameters); | ClassVar.Free; |
Class declaration | class | protocol | namespace |
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| ABAP Objects | class name definition «inheriting from parentclass». «interfaces: interfaces.» method_and_field_declarations endclass.
class name implementation. method_implementations endclass. | interface name. members endinterface. | N/A | | C++ (STL) | class name« : public parentclasses[5]» { members }; | | namespace name { members } | | C# | class name« : «parentclass»«, interfaces»» { members } | interface name« : parentinterfaces» { members } | | D | module name;
members | | Java | class name« extends parentclass»« implements interfaces» { members } | interface name« extends parentinterfaces» { members } | package name; members | | PHP | namespace name; members | | Objective-C | @interface name« : parentclass[6]»«< protocols >» { instance_fields } method_and_property_declarations @end
@implementation name method_implementations @end[7] | @protocol name«< parentprotocols >» members @end | Prefixes to class and protocol names conventionally used as a kind of namespace | | Python | class name«(parentclasses[5])»:
Tab ↹ members | [8] | __all__ = [ member1,member2,... ] | | Visual Basic .NET | Class name« Inherits parentclass»« Implements interfaces»
members
End Class | Interface name« Inherits parentinterfaces»
members
End Interface | Namespace name
members
End Namespace | | Eiffel | class name« inherit parentclasses[5]»
members
end | N/A | | Perl | package name; «@ISA = qw(parentclasses[5]);» members 1; | | package name; members | | Perl 6 | class name «is parentclass «is parentclass ...[5]»» «does role «does role ...»» { members } | role name «does role «does role ...»» { members } | module name { members } | | Ruby | class name« < parentclass»
members
end | | module name
members
end | | Windows PowerShell | N/A | | OCaml | class name «parameters» = object «(self)» «inherit parentclass «parameters» «inherit parentclass «parameters» ...[5]»» members end | | module name
members | | F# | type name«(parameters)» «as this» = class «inherit parentclass«(parameters)» «as base»» members «interface interface with implementation «interface interface with implementation ...»» end | type name = interface members end | namespace name
members | | Smalltalk | "The class is an Object.
Just send a message to the superclass (st-80) or the destination namespace (Visualworks)" | | "The namespace is an Object.
Just send a message to the parent namespace" |
Class members Constructors and destructors | constructor | destructor | finalizer[9] |
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| ABAP Objects | methods constructor «importing parameter = argument»
method constructor. instructions endmethod.[10] | N/A | | | C++ (STL) | class(«parameters») «: initializers[11]» { instructions } | ~class() { instructions } | | | C# | class(«parameters») { instructions } | void Dispose(){ instructions } | ~class() { instructions } | | D | this(«parameters») { instructions } | | ~this() { instructions } | | Java | class(«parameters») { instructions } | void dispose() { instructions } | void finalize() { instructions } | | Eiffel | [12] | | [13] | | Objective-C (Cocoa) | - (id)init { instructions... return self; } or
- (id)initWithFoo:parameter «bar:parameter ...» { instructions... return self; } | - (void)dealloc { instructions } | - (void)finalize { instructions } | | Python | def __init__(self«, parameters»):
Tab ↹ instructions | | def __del__(self):
Tab ↹ instructions | | Visual Basic .NET | Sub New(«parameters»)
instructions
End Sub | Sub Dispose()
instructions
End Sub | Overrides Sub Finalize()
instructions
End Sub | | PHP | function __construct(«parameters») { instructions } | function __destruct() { instructions } | | | Perl | sub new { my ($class«, parameters») = @_; my $self = {}; instructions ... bless($self, $class); return $self; } | sub DESTROY { my ($self) = @_; instructions } | | | Perl 6 | submethod BUILD { instructions } or
«multi » method new(««$self: »parameters») { self.bless(*, field1 => value1, ...); ... instructions } | submethod DESTROY { instructions } | | | Ruby | def initialize«(parameters)»
instructions
end | N/A | | | Windows PowerShell | N/A | | OCaml | initializer instructions[14] | N/A | | | F# | do instructions or
new(parameters) = expression[15] | member this.Dispose() = instructions | override this.Finalize() = instructions | | JavaScript | function name«(«parameters») { instructions }
(In JavaScript constructor itself is an object.) | N/A |
Fields | public | private | protected | friend |
|---|
| ABAP Objects | public section.[16] data field type type. | private section.[16] data field type type. | protected section.[16] data field type type. | [17] | | C++ (STL) | public: type field; | private: type field; | protected: type field; | [18] | | C# | public type field «= value»; | private type field «= value»; | protected type field «= value»; | internal type field «= value»; | | D | | package type field «= value»; | | Java | protected type field «= value»; | type field «= value»; | | Eiffel | feature
field: TYPE | feature {NONE}
field: TYPE | feature {current_class}
field: TYPE | feature {FRIEND}
field: TYPE | | Objective-C | @public type field; | @private type field; | @protected type field; | @package type field; | | Smalltalk | N/A | "Just send a message to the class"
class addInstVarName: field.
class removeInstVarName: field. | N/A | | Python | self.field = value
Just assign a value to it in a method | self.__field = value
Just assign a value to it in a method | N/A | | Visual Basic .NET | Public field As type «= value» | Private field As type «= value» | Protected field As type «= value» | Friend field As type «= value» | | PHP | public $field «= value»; | private $field «= value»; | protected $field «= value»; | | | Perl | $self->{field} = value;
Just assign a value to it in a method | N/A | | Perl 6 | has« type »$.field« is rw» | has« type »$!field | N/A | | Ruby | N/A | @field = value
Just assign a value to it in a method | | | Windows PowerShell | Add-Member
«-MemberType »NoteProperty
«-Name »Bar «-Value »value
-InputObject variable | N/A | | OCaml | N/A | val «mutable» field = value | N/A | | F# | N/A | let «mutable» field = value | N/A | | JavaScript | this.field = value
this["field"] = value
Just assign a value to it in a method | | | |
Methods | basic/void method | value-returning method |
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| ABAP Objects | methods name «importing parameter = argument» «exporting parameter = argument» «changing parameter = argument» «returning value(parameter)»
method name. instructions endmethod.[19] | [20] | | C++ (STL)[21] | void foo(«parameters») { instructions } | type foo(«parameters») { instructions ... return value; } | | C# | | D | | Java | | Eiffel | foo ( «parameters» )
do
instructions
end | foo ( «parameters» ): TYPE
do
instructions...
Result := value
end | | Objective-C | - (void)foo«:parameter «bar:parameter ...»» { instructions } | - (type)foo«:parameter «bar:parameter ...»» { instructions... return value; } | | Python | def foo(self«, parameters»):
Tab ↹ instructions | def foo(self«, parameters»):
Tab ↹ instructions
Tab ↹ return value | | Visual Basic .NET | Sub Foo(«parameters»)
instructions
End Sub | Function Foo(«parameters») As type
instructions
...
Return value
End Function | | PHP | function foo(«parameters») { instructions } | function foo(«parameters») { instructions ... return value; } | | Perl | sub foo { my ($self«, parameters») = @_; instructions } | sub foo { my ($self«, parameters») = @_; instructions ... return value; } | | Perl 6 | «has »«multi »method foo(««$self: »parameters») { instructions } | «has «type »»«multi »method foo(««$self: »parameters») { instructions ... return value; } | | Ruby | def foo«(parameters)»
instructions
end | def foo«(parameters)»
instructions
expression resulting in return value
end
or
def foo«(parameters)»
instructions
return value
end | | Windows PowerShell | Add-Member «-MemberType» ScriptMethod «-Name» foo «-Value» { «param(parameters)» instructions } -InputObject variable | Add-Member «-MemberType» ScriptMethod «-Name» foo «-Value» { «param(parameters)» instructions ... return value } -InputObject variable | | OCaml | N/A | method foo «parameters» = expression | | F# | member this.foo(«parameters») = expression | | JavaScript | this.method = function(«parameters») {instructions}
name«.prototype.method = function(«parameters») {instructions}
Just assign a function to it in a method | this.method = function(«parameters») {instructions... return value;}
name«.prototype.method = function(«parameters») {instructions... return value;}
Just assign a function to it in a method |
PropertiesHow to declare a property named "Bar" Manually implemented | read-write | read-only | write-only |
|---|
| ABAP Objects | N/A | | C++ (STL) | N/A | | C# | type Bar {
get { instructions ... return value; }
set { instructions } } | type Bar { get { instructions ... return value; } } | type Bar { set { instructions } } | | D | @property type bar() { instructions ... return value; }
@property type bar(type value) { instructions ... return value; } | @property type bar() { instructions ... return value; } | @property type bar(type value) { instructions ... return value; } | | Java | N/A | | Objective-C 2.0 (Cocoa) | @property (readwrite) type bar;
and then inside @implementation
- (type)bar { instructions }
- (void)setBar:(type)value { instructions } | @property (readonly) type bar;
and then inside @implementation
- (type)bar { instructions } | | | Eiffel | feature -- Access
x: TYPE assign set_x
feature -- Settings
set_x (a_x: like x) do instructions ensure x_set: verification end | | | | Python | def setBar(self, value):
Tab ↹ instructions
def getBar(self):
Tab ↹ instructions
Tab ↹ return value
bar = property(getBar, setBar) | def getBar(self):
Tab ↹ instructions
Tab ↹ return value
bar = property(getBar) | def setBar(self, value):
Tab ↹ instructions
bar = property(fset = setBar) | | Visual Basic .NET | Property Bar() As type
Get
instructions
Return value
End Get
Set (ByVal Value As type)
instructions
End Set
End Property | ReadOnly Property Bar() As type
Get
instructions
Return value
End Get
End Property | WriteOnly Property Bar() As type
Set (ByVal Value As type)
instructions
End Set
End Property | | PHP | function __get($property) {
switch ($property) {
case 'Bar' : instructions ... return value;
} }
function __set($property, $value) {
switch ($property) {
case 'Bar' : instructions
} } | function __get($property) {
switch ($property) {
case 'Bar' : instructions ... return value;
} } | function __set($property, $value) {
switch ($property) {
case 'Bar' : instructions
} } | | Perl | sub Bar {
my $self = shift;
if (my $Bar = shift) {
# setter
$self->{Bar} = $Bar;
return $self;
} else {
# getter
return $self->{Bar};
}
} | sub Bar {
my $self = shift;
if (my $Bar = shift) {
# read-only
die "Bar is read-only\n";
} else {
# getter
return $self->{Bar};
}
} | sub Bar {
my $self = shift;
if (my $Bar = shift) {
# setter
$self->{Bar} = $Bar;
return $self;
} else {
# write-only
die "Bar is write-only\n";
}
} | | Perl 6 | N/A | | Ruby | def bar
instructions
expression resulting in return value
end
def bar=(value)
instructions
end | def bar
instructions
expression resulting in return value
end | def bar=(value)
instructions
end | | Windows PowerShell | Add-Member
«-MemberType »ScriptProperty
«-Name »Bar «-Value »{ instructions ... return value }
«-SecondValue »{ instructions }
-InputObject variable | Add-Member
«-MemberType »ScriptProperty
«-Name »Bar «-Value »{ instructions ... return value}
-InputObject variable | Add-Member
«-MemberType »ScriptProperty
«-Name »Bar -SecondValue { instructions }
-InputObject variable | | OCaml | N/A | | F# | member this.Bar with get() = expression and set(value) = expression | member this.Bar = expression | member this.Bar with set(value) = expression |
Automatically implemented | read-write | read-only | write-only |
|---|
| ABAP Objects | N/A | | C++ (STL) | N/A | | C# | type Bar { get; set; } | type Bar { get; private set; } | type Bar { private get; set; } | | D | | | | | Java | N/A | | Objective-C 2.0 (Cocoa) | @property (readwrite) type bar;
and then inside @implementation
@synthesize bar; | @property (readonly) type bar;
and then inside @implementation
@synthesize bar; | | | Eiffel | | | | | Python | @property
def bar(self):
Tab ↹instructions
@bar.setter
def bar(self, value):
Tab ↹instructions | @property
def bar(self):
Tab ↹instructions | bar = property()
@bar.setter
def bar(self, value):
Tab ↹instructions | | Visual Basic .NET | Property Bar As type« = initial_value» (VB 10) | | | | PHP | | | | | Perl[22] | use base qw(Class::Accessor);
__PACKAGE__->mk_accessors('Bar'); | use base qw(Class::Accessor);
__PACKAGE__->mk_ro_accessors('Bar'); | use base qw(Class::Accessor);
__PACKAGE__->mk_wo_accessors('Bar'); | | Perl 6 | N/A | | Ruby | attr_accessor :bar | attr_reader :bar | attr_writer :bar | | Windows PowerShell | | | | | OCaml | N/A | | F# | member val Bar = value with get, set | | |
Overloaded operators Standard operators| | unary | binary | function call |
|---|
| ABAP Objects | N/A | | C++ (STL) | type operatorsymbol() { instructions } | type operatorsymbol(type operand2) { instructions } | type operator()(«parameters») { instructions } | | C# | static type operator symbol(type operand) { instructions } | static type operator symbol(type operand1, type operand2) { instructions } | N/A | | D | type opUnary(string s)() if (s == "symbol") { instructions } | type opBinary(string s)(type operand2) if (s == "symbol") { instructions }
type opBinaryRight(string s)(type operand1) if (s == "symbol") { switch (s) { instructions } | type opCall(«parameters») { instructions } | | Java | N/A | | Objective-C | | Eiffel[23] | op_name alias "symbol": TYPE
do instructions end | op_name alias "symbol" (operand: TYPE1): TYPE2
do instructions end | | | Python | def __opname__(self):
Tab ↹ instructions
Tab ↹ return value | def __opname__(self, operand2):
Tab ↹ instructions
Tab ↹ return value | def __call__(self«, paramters»):
Tab ↹ instructions
Tab ↹ return value | | Visual Basic .NET | Shared Operator symbol(operand As type) As type
instructions
End Operator | Shared Operator symbol(operand1 As type, operand2 As type) As type
instructions
End Operator | N/A | | PHP | [24] | function __invoke(«parameters») { instructions } (PHP 5.3+) | | Perl | use overload "symbol" => sub { my ($self) = @_; instructions }; | use overload "symbol" => sub { my ($self, $operand2, $operands_reversed) = @_; instructions }; | | | Perl 6 | «our «type »»«multi »method prefix:<symbol> («$operand: ») { instructions ... return value; } or
«our «type »»«multi »method postfix:<symbol> («$operand: ») { instructions ... return value; } or
«our «type »»«multi »method circumfix:<symbol1 symbol2> («$operand: ») { instructions ... return value; } | «our «type »»«multi »method infix:<symbol> («$operand1: » type operand2) { instructions ... return value; } | «our «type »»«multi »method postcircumfix:<( )> («$self: » «parameters») { instructions } | | Ruby | def symbol
instructions
expression resulting in return value
end | def symbol(operand2)
instructions
expression resulting in return value
end | N/A | | Windows PowerShell | N/A | | OCaml | | F# | static member (symbol) operand = expression | static member (symbol) (operand1, operand2) = expression | N/A |
Indexers| | read-write | read-only | write-only |
|---|
| ABAP Objects | N/A | | C++ (STL) | type& operator[](type index) { instructions } | type operator[](type index) { instructions } | | | C# | type this[type index] {
get{ instructions }
set{ instructions } } | type this[type index] { get{ instructions } } | type this[type index] { set{ instructions } } | | D | type opIndex(type index) { instructions }
type opIndexAssign(type value, type index) { instructions } | type opIndex(type index) { instructions } | type opIndexAssign(type value, type index) { instructions } | | Java | N/A | | Objective-C | | Eiffel[23] | bracket_name alias "[]" (index: TYPE): TYPE assign set_item
do instructions end
set_item (value: TYPE; index: TYPE):
do instructions end | bracket_name alias "[]" (index: TYPE): TYPE
do instructions end | | | Python | def __getitem__(self, index):
Tab ↹ instructions
Tab ↹ return value
def __setitem__(self, index, value):
Tab ↹ instructions | def __getitem__(self, index):
Tab ↹ instructions
Tab ↹ return value | def __setitem__(self, index, value):
Tab ↹ instructions | | Visual Basic .NET | Default Property Item(Index As type) As type
Get
instructions
End Get
Set(ByVal Value As type)
instructions
End Set
End Property | Default ReadOnly Property Item(Index As type) As type
Get
instructions
End Get
End Property | Default WriteOnly Property Item(Index As type) As type
Set(ByVal Value As type)
instructions
End Set
End Property | | PHP | [25] | | Perl | [26] | | Perl 6 | «our «type »»«multi »method postcircumfix:<[ ]> is rw («$self: » type $index) { instructions ... return value; } or
«our «type »»«multi »method postcircumfix:<{ }> is rw («$self: » type $key) { instructions ... return value; } | «our «type »»«multi »method postcircumfix:<[ ]>(«$self: » type $index) { instructions ... return value; } or
«our «type »»«multi »method postcircumfix:<{ }> («$self: » type $key) { instructions ... return value; } | N/A | | Ruby | def [](index)
instructions
expression resulting in return value
end
def []=(index, value)
instructions
end | def [](index)
instructions
expression resulting in return value
end | def []=(index, value)
instructions
end | | Windows PowerShell | N/A | | OCaml | | F# | member this.Item with get(index) = expression and set index value = expression | member this.Item with get(index) = expression | member this.Item with set index value = expression |
Type casts| | downcast | upcast |
|---|
| ABAP Objects | N/A | | C++ (STL) | | operator returntype() { instructions } | | C# | static explicit operator returntype(type operand) { instructions } | static implicit operator returntype(type operand) { instructions } | | D | | T opCast(T)() { if (is(T == type)) { instructions } ... } | | Java | N/A | | Objective-C | | Eiffel[23] | | Python | | Visual Basic .NET | Shared Narrowing Operator CType(operand As type) As returntype
instructions
End Operator | Shared Widening Operator CType(operand As type) As returntype
instructions
End Operator | | Perl 6 | | multi method type«($self:)» is export { instructions } | | PHP | N/A | | Perl | | Ruby | | Windows PowerShell | | OCaml | | F# | | |
Member accessHow to access members of an object x | object member | class member | namespace member |
|---|
| method | field | property |
|---|
| ABAP Objects | x->method(«parameters[27]»). | x->field | N/A | x=>field or x=>method(«parameters[27]»). | N/A | | C++ (STL) | x.method(parameters) or
ptr->method(parameters) | x.field or
ptr->field | | cls::member | ns::member | | Objective-C | [x method«:parameter «bar:parameter ...»»] | x->field | x.property (2.0 only) or
[x property] | [cls method«:parameter «bar:parameter ...»»] | | | Smalltalk | x method«:parameter «bar:parameter ...»» | N/A | | cls method«:parameter «bar:parameter ...»» | | | C# | x.method(parameters) | x.field | x.property | cls.member | ns.member | | Java | N/A | | D | x.property | | Python | | Visual Basic .NET | | Windows PowerShell | [cls]::member | | F# | N/A | cls.member | | Eiffel | x.method«(parameters)» | x.field | | {cls}.member | N/A | | Ruby | N/A | x.property | cls.member | | PHP | x->method(parameters) | x->field | x->property | cls::member | ns\member | | Perl | x->method«(parameters)» | x->{field} | | cls->method«(parameters)» | ns::member | | Perl 6 | x.method«(parameters)» or
x!method«(parameters)» | x.field or
x!field | | cls.method«(parameters)» or
cls!method«(parameters)» | ns::member | | OCaml | x#method «parameters» | N/A | | | | JavaScript | x.method(parameters)
x["method"](parameters) | x.field
x["field"] | x.property
x["property"] | N/A | N/A |
Member availability | Has member? | Handler for missing member |
|---|
| Method | Field | Method | Field |
|---|
| ABAP Objects | N/A | | C++ (STL) | | Objective-C (Cocoa) | [x respondsToSelector:@selector(method)] | N/A | forwardInvocation: | N/A | | Smalltalk | x respondsTo: selector | N/A | doesNotUnderstand: | N/A | | C# | (using reflection) | | Java | | D | | | opDispatch() | | Eiffel | N/A | | Python | hasattr(x, "method") and callable(x.method) | hasattr(x, "field") | __getattr__() | | Visual Basic .NET | (using reflection) | | Windows PowerShell | (using reflection) | | F# | (using reflection) | | Ruby | x.respond_to?(:method) | N/A | method_missing() | N/A | | PHP | method_exists(x, "method") | property_exists(x, "field") | __call() | __get() / __set() | | Perl | x->can("method") | exists x->{field} | AUTOLOAD | | | Perl 6 | x.can("method") | x.field.defined | AUTOLOAD | | | OCaml | N/A | | JavaScript | typeof x.method === "function" | field in x | | |
Special variables Special methods | String representation | Object copy | Value equality | Object comparison | Hash code | Object ID |
|---|
| Human-readable | Source-compatible |
|---|
| ABAP Objects | N/A | | C++ (STL) | | | | x == y[36] | | | pointer to object can be converted into an integer ID | | C# | x.ToString() | | x.Clone() | x.Equals(y) | x.CompareTo(y) | x.GetHashCode() | System.Runtime.CompilerServices.Runti meHelpers.GetHashCode(x) | | Java | x.toString() | | x.clone()[37] | x.equals(y) | x.compareTo(y) | x.hashCode() | System.identityHashCode(x) | | JavaScript | x.toString() | | | | | | | | D | x.toString() or
std.conv.to!string(x) | x.stringof | | x == y | | x.toHash() | | | Objective-C (Cocoa) | [x description] | [x debugDescription] | [x copy][38] | [x isEqual:y] | [x compare:y][39] | [x hash] | pointer to object can be converted into an integer ID | | Smalltalk | x displayString | x printString | x copy | x = y | | x hash | x identityHash | | Python | str(x)[40] | repr(x)[41] | copy.copy(x)[42] | x == y[43] | cmp(x, y)[44] | hash(x)[45] | id(x) | | Visual Basic .NET | x.ToString() | | x.Clone() | x.Equals(y) | x.CompareTo(y) | x.GetHashCode() | | | Eiffel | x.out | | x.twin | x.is_equal(y) | When x is COMPARABLE, one can simply do x < y | When x is HASHABLE, one can simply do x.hash_code | When x is IDENTIFIED, one can simply do x.object_id | | PHP | sprintf("%s", x)[46] | | clone x[47] | x == y | | | spl_object_hash(x) | | Perl | "$x"[48] | Data::Dumper->Dump([$x],['x'])[49] | Storable::dclone($x)[50] | | | | Scalar::Util::refaddr( $x )[51] | | Perl 6 | ~x[48] | x.perl | x.clone | x eqv y | x cmp y | | x.WHICH | | Ruby | x.to_s | x.inspect | x.dup or
x.clone | x == y or
x.eql?(y) | x <=> y | x.hash | x.object_id | | Windows PowerShell | x.ToString() | | x.Clone() | x.Equals(y) | x.CompareTo(y) | x.GetHashCode() | | | OCaml | | | Oo.copy x | x = y | | Hashtbl.hash x | Oo.id x | | F# | string x or x.ToString() or sprintf "%O" x | sprintf "%A" x | x.Clone() | x = y or x.Equals(y) | compare x y or x.CompareTo(y) | hash x or x.GetHashCode() | |
Type manipulation | Get object type | Is instance of (includes subtypes) | Upcasting | Downcasting |
|---|
| Runtime check | No check |
|---|
| ABAP Objects | N/A[52] | = | ?= | | C++ (STL) | typeid(x) | dynamic_cast<type *>(&x) != NULL | N/A[53] | dynamic_cast<type*>(ptr) | (type*) ptr or
static_cast<type*>(ptr) | | C# | x.GetType() | x is type | (type) x or x as type | | | D | typeid(x) | | cast(type) x | | | Delphi | | x is type | x as type | | | Java | x.getClass() | x instanceof class | (type) x | | | Objective-C (Cocoa) | [x class] | [x isKindOfClass:[class class]] | | (type*) x | | JavaScript | x.constructor (If not rewritten.) | x instanceof class | N/A[54] | | Visual Basic .NET | x.GetType() | TypeOf x Is type | N/A[53] | CType(x, type) or TryCast(x, type) | | | Eiffel | x.generating_type | attached {TYPE} x | attached {TYPE} x as down_x | | | Python | type(x) | isinstance(x, type) | N/A[54] | | PHP | get_class(x) | x instanceof class | | Perl | ref(x) | x->isa("class") | | Perl 6 | x.WHAT | x.isa(class) | N/A[53] | type(x) or
x.type | | | Ruby | x.class | x.instance_of?(type) or
x.kind_of?(type) | N/A[54] | | Smalltalk | x class | x isKindOf: class | | Windows PowerShell | x.GetType() | x -is [type] | N/A[53] | [type]x or x -as [type] | | | OCaml | N/A[55] | (x :> type) | N/A | | F# | x.GetType() | x :? type | (x :?> type) | |
Namespace management | Import namespace | Import item |
|---|
| qualified | unqualified |
|---|
| ABAP Objects | | | | | C++ (STL) | | using namespace ns; | using ns::item ; | | C# | | using ns; | using item = ns.item; | | D | | import ns; | import ns : item; | | Java | | import ns.*; | import ns.item | | Objective-C | | | | | Visual Basic .NET | | Imports ns | | | Eiffel | | | | | Python | import ns | from ns import * | from ns import item | | PHP | | use ns; | use ns\item; | | Perl | use ns; | | use ns qw(item); | | Perl 6 | | | | Ruby | | | | | Windows PowerShell | | | | | OCaml | | open ns | | | F# | | |
Contracts | Precondition | Postcondition | Check | Invariant | Loop |
|---|
| ABAP Objects | N/A | | C++ (STL) | | C# | Spec#:
type foo( «parameters» )
requires expression
{
body
} | Spec#:
type foo( «parameters» )
ensures expression
{
body
} | | Java | N/A | | Objective-C | | Visual Basic .NET | | D | f in { expression } body{ instructions } | f out (result) { expression } body{ instructions } | | invariant() { expression } | | | Eiffel | f
require tag: expression
do end | f
do
ensure tag: expression
end | f
do
check tag: expression end
end | class X
invariant tag: expression
end | from instructions
invariant
tag: expression
until
expr
loop
instructions
variant
tag: expression
end | | Python | N/A | | PHP | | Perl | | Perl 6 | PRE { condition } | POST { condition } | | | | | Ruby | N/A | | Windows PowerShell | | OCaml | | F# |
See also References and notes- ^ parameter = argument may be repeated if the constructor has several parameters
- ^ SAP reserved to himself the use of destruction
- ^ a b c d e f g h i This language uses garbage collection to release unused memory.
- ^ OCaml objects can be created directly without going through a class.
- ^ a b c d e f g This language supports multiple inheritance. A class can have more than one parent class
- ^ Not providing a parent class makes the class a root class. In practice, this is almost never done. One should generally use the conventional base class of the framework one is using, which is
NSObject for Cocoa and GNUstep, or Object otherwise. - ^ Usually the
@interface portion is placed into a header file, and the @interface portion is placed into a separate source code file. - ^ In Python interfaces are classes whose methods have pass as their bodies
- ^ A finalizer is called by the garbage collector when an object is about to be garbage-collected. There is no guarantee on when it will be called or if it will be called at all.
- ^ In ABAP, the constructor is to be defined like a method (see comments about method) with the following restrictions: the method name must be "constructor", and only "importing" parameters can be defined
- ^ An optional comma-separated list of initializers for member objects and parent classes goes here. The syntax for initializing member objects is "member_name(parameters)" This works even for primitive members, in which case one parameter is specified and that value is copied into the member. The syntax for initializing parent classes is "class_name(parameters)". If an initializer is not specified for a member or parent class, then the default constructor is used.
- ^ Any Eiffel procedure can be used as a creation procedure, aka constructors. See Eiffel paragraph at Constructor (computer science).
- ^ Implementing {DISPOSABLE}.dispose ensures that dispose will be called when object is garbage collected.
- ^ This "initializer" construct is rarely used. Fields in OCaml are usually initialized directly in their declaration. Only when additional imperative operations are needed is "initializer" used. The "parameters to the constructor" in other languages are instead specified as the parameters to the class in OCaml. See the class declaration syntax for more details.
- ^ This syntax is usually used to overload constructors
- ^ a b c Scope identifier must appear once in the file declaration, all variable declarations after this scope identifier have his scope, until another scope identifier or the end of class declaration is reached
- ^ In ABAP, you don't declare specific fields or methods to be accessible by outside things. Rather, you declare outside classes to be friends to have access to the class's fields or methods.
- ^ In C++, you don't declare specific fields to be accessible by outside things. Rather, you declare outside functions and classes to be friends to have access to the class's fields. See friend function and friend class for more details.
- ^ The declaration and implementation of methods in ABAP are separate. methods statement is to be used inside the class definition. method (without "s") is to be used inside the class implementation. parameter = argument can be repeated if there are several parameters.
- ^ In ABAP, the return parameter name is explicitly defined in the method signature within the class definition
- ^ The declaration and implementation of methods in C++ are usually separate. Methods are declared inside the class definition (which is usually included in a header file) using the syntax
- type foo(«parameters»);
The implementation of methods is usually provided in a separate source file, with the following syntax- type class::foo(«parameters») { instructions }
Although the body of a method could be included with the declaration inside the class definition, as shown in the table here, this is generally a bad idea. Because the class definition will need to be included with every source file which uses the fields or methods of the class, having code in the class definition will cause the method code to be compiled with every source file, increasing the size of the code. There are some circumstances, however, where it is useful to include the body of a method with the declaration. One reason is that the compiler will try to inline methods that are included in the class declaration; so if you have a very short one-liner method, it may make it faster to allow the compiler to inline it, by including the body along with the declaration. Also, if you have a template class or method, then all the code must be included with the declaration, because only with the code can the template be instantiated. - ^ these examples need the Class::Accessor module installed
- ^ a b c Although Eiffel does not support overloading of operators, it can define operators
- ^ PHP does not support operator overloading natively, but support can be added using the "operator" PECL package.
- ^ Your class needs to implement the ArrayAccess interface.
- ^ Your class needs to overload '@{}' (array dereference) or subclass one of Tie::Array or Tie::StdArray to hook array operations
- ^ a b In ABAP, arguments must be passed using this syntax:
- x->method(«exporting parameter = argument» «importing parameter = argument» «changing parameter = argument» «returning value(parameter)»
- parameter = argument can be repeated if there are several parameters
- ^ C++ doesn't have a "super" keyword, because multiple inheritance is possible, and so it may be ambiguous which base class is desired. Instead, you can use the
BaseClassName::member syntax to access an overridden member in the specified base class. Microsoft Visual C++ provides a non-standard keyword "__super" for this purpose; but this is not supported in other compilers.[1] - ^ a b c d e f The keyword here is not a value in itself and it can only be used to access a method of the superclass.
- ^ a b In this language, instance methods are passed the current object as the first parameter, which is conventionally named "self", but this is not required to be the case.
- ^ "Precursor" in Eiffel is actually a call to the method of the same name in the superclass. So Precursor(args) is equivalent to "super.currentMethodName(args)" in Java. There is no way of calling a method of different name in the superclass.
- ^ "super" in Ruby, unlike in other languages, is actually a call to the method of the same name in the superclass. So super(args) in Ruby is equivalent to "super.currentMethodName(args)" in Java. There is no way of calling a method of different name in the superclass.
- ^ In OCaml, an object declaration can optionally start with a parameter which will be associated with the current object. This parameter is conventionally named "self", but this is not required to be the case. It is good practice to put a parameter there so that one can call one's own methods.
- ^ In OCaml, an inheritance declaration ("inherit") can optionally be associated with a value, with the syntax "inherit parent_class «parameters» as super". Here "super" is the name we gave to the variable associated with this parent object. It can be named something else.
- ^ However, if you really wanted the ability to have an "optional" value in OCaml, you would wrap the value inside an
option type, whose values are None and Some x, which could be used to represent "null reference" and "non-null reference to an object" as in other languages. - ^ assuming that "x" and "y" are the objects (and not a pointer). Can be customized by overloading the object's
== operator - ^ Only accessible from within the class itself, since the
clone() method inherited from Object is protected, unless the class overrides the method and makes it public. If you use the clone() inherited from Object, your class will need to implement the Cloneable interface to allow cloning. - ^ Implemented by the object's
copyWithZone: method - ^
compare: is the conventional name for the comparison method in Foundation classes. However, no formal protocol exists - ^ Can be customized by the object's
__str__() method - ^ Can be customized by the object's
__repr__() method - ^ Can be customized by the object's
__copy__() method - ^ Can be customized by the object's
__eq__() method - ^ Only in Python 2.x and before (removed in Python 3.0). Can be customized by the object's
__cmp__() method - ^ Can be customized by the object's
__hash__() method. Not all types are hashable (mutable types are usually not hashable) - ^ Can be customized by the object's
__toString() method - ^ Can be customized by the object's
__clone() method - ^ a b Can be customized by overloading the object's string conversion operator
- ^ This example requires useing Data::Dumper
- ^ This example requires useing Storable
- ^ This example requires useing Scalar::Util
- ^ Run-time type information in ABAP can be gathered by using different description Classes like CL_ABAP_CLASSDESCR.
- ^ a b c d Upcasting is implicit in this language. A subtype instance can be used where a supertype is needed.
- ^ a b c This language is dynamically typed. Casting between types is not necessary.
- ^ This language doesn't give run-time type information. It is unnecessary because it is statically typed and downcasting is not possible.
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