abstract class Class

Defined in:

class.cr
primitives.cr

Constructors

Class Method Summary

Instance Method Summary

Instance methods inherited from struct Value

==(other : JSON::Any)
==(other : YAML::Any)
==(other)
==
, dup dup

Instance methods inherited from class Object

! : Bool !, !=(other) !=, !~(other) !~, ==(other) ==, ===(other : JSON::Any)
===(other : YAML::Any)
===(other)
===
, =~(other) =~, as(type : Class) as, as?(type : Class) as?, class class, dup dup, hash(hasher)
hash
hash
, in?(collection : Object) : Bool
in?(*values : Object) : Bool
in?
, inspect(io : IO) : Nil
inspect : String
inspect
, is_a?(type : Class) : Bool is_a?, itself itself, nil? : Bool nil?, not_nil!(message)
not_nil!
not_nil!
, pretty_inspect(width = 79, newline = "\n", indent = 0) : String pretty_inspect, pretty_print(pp : PrettyPrint) : Nil pretty_print, responds_to?(name : Symbol) : Bool responds_to?, tap(&) tap, to_json(io : IO) : Nil
to_json : String
to_json
, to_pretty_json(indent : String = " ") : String
to_pretty_json(io : IO, indent : String = " ") : Nil
to_pretty_json
, to_s(io : IO) : Nil
to_s : String
to_s
, to_yaml(io : IO) : Nil
to_yaml : String
to_yaml
, try(&) try, unsafe_as(type : T.class) forall T unsafe_as

Class methods inherited from class Object

from_json(string_or_io, root : String)
from_json(string_or_io)
from_json
, from_yaml(string_or_io : String | IO) from_yaml

Macros inherited from class Object

class_getter(*names, &block) class_getter, class_getter!(*names) class_getter!, class_getter?(*names, &block) class_getter?, class_property(*names, &block) class_property, class_property!(*names) class_property!, class_property?(*names, &block) class_property?, class_setter(*names) class_setter, def_clone def_clone, def_equals(*fields) def_equals, def_equals_and_hash(*fields) def_equals_and_hash, def_hash(*fields) def_hash, delegate(*methods, to object) delegate, forward_missing_to(delegate) forward_missing_to, getter(*names, &block) getter, getter!(*names) getter!, getter?(*names, &block) getter?, property(*names, &block) property, property!(*names) property!, property?(*names, &block) property?, setter(*names) setter

Constructor Detail

def self.cast(other) : self #

Casts other to this class.

This is the same as using as, but allows the class to be passed around as an argument. See the documentation on as for more information.

klass = Int32
number = [99, "str"][0]
typeof(number)             # => (String | Int32)
typeof(klass.cast(number)) # => Int32

Class Method Detail

def self.<(other : T.class) : Bool forall T #

Returns whether this class inherits or includes other.

Int32 < Number  # => true
Int32 < Value   # => true
Int32 < Int32   # => false
Int32 <= String # => false

def self.<=(other : T.class) : Bool forall T #

Returns whether this class inherits or includes other, or is equal to other.

Int32 < Number  # => true
Int32 < Value   # => true
Int32 <= Int32  # => true
Int32 <= String # => false

def self.==(other : Class) : Bool #

Returns whether this class is the same as other.

Int32 == Int32  # => true
Int32 == String # => false

def self.===(other) #
Description copied from class Object

Case equality.

The #=== method is used in a case ... when ... end expression.

For example, this code:

case value
when x
  # something when x
when y
  # something when y
end

Is equivalent to this code:

if x === value
  # something when x
elsif y === value
  # something when y
end

Object simply implements #=== by invoking #==, but subclasses (notably Regex) can override it to provide meaningful case-equality semantics.


def self.>(other : T.class) : Bool forall T #

Returns whether other inherits or includes self.

Number > Int32  # => true
Number > Number # => false
Number > Object # => false

def self.>=(other : T.class) forall T #

Returns whether other inherits or includes self, or is equal to self.

Number >= Int32  # => true
Number >= Number # => true
Number >= Object # => false

def self.|(other : U.class) forall U #

Returns the union type of self and other.

Int32 | Char # => (Int32 | Char)

def self.clone #

def self.dup #
Description copied from struct Value

Returns a shallow copy of this object.

Because Value is a value type, this method returns self, which already involves a shallow copy of this object because value types are passed by value.


def self.hash(hasher) #

def self.inspect(io : IO) : Nil #
Description copied from class Object

Prints to io an unambiguous and information-rich string representation of this object, typically intended for developers.

It is similar to #to_s(IO), but often provides more information. Ideally, it should contain sufficient information to be able to recreate an object with the same value (given an identical environment).

For types that don't provide a custom implementation of this method, default implementation delegates to #to_s(IO). This said, it is advisable to have an appropriate #inspect implementation on every type. Default implementations are provided by Struct#inspect and Reference#inspect.

::p and ::p! use this method to print an object in STDOUT.


def self.name : String #

Returns the name of this class.

String.name # => "String"

def self.nilable? : Bool #

Returns true if nil is an instance of this type.

Int32.nilable?            # => false
Nil.nilable?              # => true
(Int32 | String).nilable? # => false
(Int32 | Nil).nilable?    # => true
NoReturn.nilable?         # => false
Value.nilable?            # => true

def self.to_s(io : IO) : Nil #
Description copied from class Object

Prints a nicely readable and concise string representation of this object, typically intended for users, to io.

This method is called when an object is interpolated in a string literal:

"foo #{bar} baz" # calls bar.to_io with the builder for this string

IO#<< calls this method to append an object to itself:

io << bar # calls bar.to_s(io)

Thus implementations must not interpolate self in a string literal or call io << self which both would lead to an endless loop.

Also see #inspect(IO).


Instance Method Detail

def <(other : T.class) : Bool forall T #

Returns whether this class inherits or includes other.

Int32 < Number  # => true
Int32 < Value   # => true
Int32 < Int32   # => false
Int32 <= String # => false

def <=(other : T.class) : Bool forall T #

Returns whether this class inherits or includes other, or is equal to other.

Int32 < Number  # => true
Int32 < Value   # => true
Int32 <= Int32  # => true
Int32 <= String # => false

def ==(other : Class) : Bool #

Returns whether this class is the same as other.

Int32 == Int32  # => true
Int32 == String # => false

def ===(other) #
Description copied from class Object

Case equality.

The #=== method is used in a case ... when ... end expression.

For example, this code:

case value
when x
  # something when x
when y
  # something when y
end

Is equivalent to this code:

if x === value
  # something when x
elsif y === value
  # something when y
end

Object simply implements #=== by invoking #==, but subclasses (notably Regex) can override it to provide meaningful case-equality semantics.


def >(other : T.class) : Bool forall T #

Returns whether other inherits or includes self.

Number > Int32  # => true
Number > Number # => false
Number > Object # => false

def >=(other : T.class) forall T #

Returns whether other inherits or includes self, or is equal to self.

Number >= Int32  # => true
Number >= Number # => true
Number >= Object # => false

def |(other : U.class) forall U #

Returns the union type of self and other.

Int32 | Char # => (Int32 | Char)

def cast(other) : self #

Casts other to this class.

This is the same as using as, but allows the class to be passed around as an argument. See the documentation on as for more information.

klass = Int32
number = [99, "str"][0]
typeof(number)             # => (String | Int32)
typeof(klass.cast(number)) # => Int32

def clone #

def dup #
Description copied from struct Value

Returns a shallow copy of this object.

Because Value is a value type, this method returns self, which already involves a shallow copy of this object because value types are passed by value.


def hash(hasher) #

def inspect(io : IO) : Nil #
Description copied from class Object

Prints to io an unambiguous and information-rich string representation of this object, typically intended for developers.

It is similar to #to_s(IO), but often provides more information. Ideally, it should contain sufficient information to be able to recreate an object with the same value (given an identical environment).

For types that don't provide a custom implementation of this method, default implementation delegates to #to_s(IO). This said, it is advisable to have an appropriate #inspect implementation on every type. Default implementations are provided by Struct#inspect and Reference#inspect.

::p and ::p! use this method to print an object in STDOUT.


def name : String #

Returns the name of this class.

String.name # => "String"

def nilable? : Bool #

Returns true if nil is an instance of this type.

Int32.nilable?            # => false
Nil.nilable?              # => true
(Int32 | String).nilable? # => false
(Int32 | Nil).nilable?    # => true
NoReturn.nilable?         # => false
Value.nilable?            # => true

def to_s(io : IO) : Nil #
Description copied from class Object

Prints a nicely readable and concise string representation of this object, typically intended for users, to io.

This method is called when an object is interpolated in a string literal:

"foo #{bar} baz" # calls bar.to_io with the builder for this string

IO#<< calls this method to append an object to itself:

io << bar # calls bar.to_s(io)

Thus implementations must not interpolate self in a string literal or call io << self which both would lead to an endless loop.

Also see #inspect(IO).