|
instance methods
|
|
==
|
obj == anObject
-> true or false
|
|
Equality---At the Object level, == returns true only if
obj and anObject are the same object. Typically, this
method is overridden in descendent classes to provide
class-specific meaning.
|
|
===
|
obj === anObject
-> true or false
|
|
Case Equality---A synonym for
Object#==
, but typically overridden by
descendents to provide meaningful semantics in case
statements.
|
|
=~
|
obj =~ anObject
-> false
|
|
Pattern Match---Overridden by descendents (notably Regexp
and String) to provide meaningful
pattern-match semantics.
|
|
__id__
|
obj.__id__
-> aFixnum
|
|
Synonym for
Object#id
.
|
|
__send__
|
obj.__send__(
aSymbol [, args
]+
) -> anObject
|
|
Synonym for
Object#send
.
|
|
class
|
obj.class -> aClass
|
|
Returns the class of obj (synonym for
Object#type
).
|
|
clone
|
obj.clone -> anObject
|
|
Produces a shallow copy of obj---the instance variables of obj
are copied, but not the objects they reference.
Copies the frozen and tainted state of obj. See also the
discussion under
Object#dup
.
class Klass
|
attr_accessor :str
|
end
|
s1 = Klass.new
|
» |
#<Klass:0x401b5478>
|
s1.str = "Hello"
|
» |
"Hello"
|
s2 = s1.clone
|
» |
#<Klass:0x401b5194 @str="Hello">
|
s2.str[1,4] = "i"
|
» |
"i"
|
s1.inspect
|
» |
"#<Klass:0x401b5478 @str=\"Hi\">"
|
s2.inspect
|
» |
"#<Klass:0x401b5194 @str=\"Hi\">"
|
|
|
display
|
obj.display( port=$> )
-> nil
|
|
Prints obj on the given port (default $>). Equivalent
to:
def display(port=$>)
port.write self
end
|
|
|
dup
|
obj.dup -> anObject
|
|
Produces a shallow copy
of obj---the instance variables of obj
are copied, but not the objects they reference. dup
copies the tainted state of obj. See also the
discussion under
Object#clone
.
In general,
clone and dup may have different semantics in
descendent classes. While clone is used to duplicate an
object, including its internal state, dup typically
uses the class of the descendent object to create the new instance.
|
|
eql?
|
obj.eql?( anObject )
-> true or false
|
|
Returns true if obj and anObject have the
same value. Used by Hash to test
members for equality. For objects of class Object,
eql? is synonymous with ==. Subclasses
normally continue this tradition, but there are
exceptions. Numeric types, for example, perform type
conversion across ==, but not across eql?, so:
1 == 1.0
|
» |
true
|
1.eql? 1.0
|
» |
false
|
|
|
equal?
|
obj.equal?( anObject )
-> true or false
|
|
Returns true if obj and anObject have the
same object ID. This method should
not be overridden by subclasses.
a = [ 'cat', 'dog' ]
|
b = [ 'cat', 'dog' ]
|
a == b
|
» |
true
|
a.id == b.id
|
» |
false
|
a.eql?(b)
|
» |
true
|
a.equal?(b)
|
» |
false
|
|
|
extend
|
obj.extend( [
aModule
]+
)
-> obj
|
|
Adds to obj the instance methods from each module given as a parameter.
module Mod
|
def hello
|
"Hello from Mod.\n"
|
end
|
end
|
|
class Klass
|
def hello
|
"Hello from Klass.\n"
|
end
|
end
|
|
k = Klass.new
|
k.hello
|
» |
"Hello from Klass.\n"
|
k.extend(Mod)
|
» |
#<Klass:0x401b598c>
|
k.hello
|
» |
"Hello from Mod.\n"
|
|
|
freeze
|
obj.freeze -> obj
|
|
Prevents further modifications to obj. A TypeError
will be raised if modification is attempted. There is no way to
unfreeze a frozen object.
See also
Object#frozen?
.
a = [ "a", "b", "c" ]
a.freeze
a << "z"
|
produces:
prog.rb:3:in `<<': can't modify frozen array (TypeError)
from prog.rb:3
|
|
|
frozen?
|
obj.frozen?
-> true or false
|
|
Returns the freeze status of obj.
a = [ "a", "b", "c" ]
|
a.freeze
|
» |
["a", "b", "c"]
|
a.frozen?
|
» |
true
|
|
|
hash
|
obj.hash -> aFixnum
|
|
Generates a Fixnum hash value for this object. This function
must have the property that a.eql?(b) implies a.hash ==
b.hash. The hash value is used by class Hash.
Any hash value that exceeds the
capacity of a Fixnum will be truncated before being used.
|
|
id
|
obj.id -> aFixnum
|
|
Returns an integer identifier for obj. The same number will be
returned on all calls to id for a given object, and no
two active objects will share an id.
Object#id
is a
different concept from the :name notation, which returns the
symbol id of name.
|
|
inspect
|
obj.inspect -> aString
|
|
Returns a string containing a human-readable representation of
obj. If not overridden, uses the to_s method to generate
the string.
[ 1, 2, 3..4, 'five' ].inspect
|
» |
"[1, 2, 3..4, \"five\"]"
|
Time.new.inspect
|
» |
"Sun Jun 09 00:18:15 CDT 2002"
|
|
|
instance_eval
|
obj.instance_eval(aString
[, file
[
line
]
] )
-> anObject
obj.instance_eval {| | block }
-> anObject
|
|
Evaluates a string containing Ruby source code, or the given
block, within the
context of the receiver (obj). In order to set the context, the
variable self is set to obj while the code is
executing, giving the code access to obj's instance variables.
In the version of instance_eval that takes a
String, the optional second and third parameters supply a
filename and starting line number that are used when reporting
compilation errors.
class Klass
|
def initialize
|
@secret = 99
|
end
|
end
|
k = Klass.new
|
k.instance_eval { @secret }
|
» |
99
|
|
|
instance_of?
|
obj.instance_of?( aClass )
-> true or false
|
|
Returns true if obj is an instance of the
given class. See also
Object#kind_of?
.
|
|
instance_variables
|
obj.instance_variables
-> anArray
|
|
Returns an array of instance variable names for the
receiver.
|
|
is_a?
|
obj.is_a?( aClass )
-> true or false
|
|
Synonym for
Object#kind_of?
.
|
|
kind_of?
|
obj.kind_of?( aClass )
-> true or false
|
|
Returns true if aClass is the class of obj, or
if aClass is one of the superclasses of obj or modules included
in obj.
a = 1
|
a.instance_of? Numeric
|
» |
false
|
a.instance_of? Integer
|
» |
false
|
a.instance_of? Fixnum
|
» |
true
|
a.instance_of? Comparable
|
» |
false
|
a.kind_of? Numeric
|
» |
true
|
a.kind_of? Integer
|
» |
true
|
a.kind_of? Fixnum
|
» |
true
|
a.kind_of? Comparable
|
» |
true
|
|
|
method
|
obj.method( aSymbol )
-> aMethod
|
|
Looks up the named method as a receiver in obj, returning a
Method object (or raising NameError). The Method object acts
as a closure in obj's object instance, so instance variables
and the value of self remain available.
class Demo
|
def initialize(n)
|
@iv = n
|
end
|
def hello()
|
"Hello, @iv = #{@iv}"
|
end
|
end
|
|
k = Demo.new(99)
|
m = k.method(:hello)
|
m.call
|
» |
"Hello, @iv = 99"
|
|
l = Demo.new('Fred')
|
m = l.method("hello")
|
m.call
|
» |
"Hello, @iv = Fred"
|
|
|
method_missing
|
obj.method_missing( aSymbol [, *args
] )
-> anObject
|
|
Invoked by Ruby when obj is sent a message it cannot
handle. aSymbol is the symbol for the method called,
and args are any arguments that were passed to it. The
example below creates a class Roman, which responds to methods
with names consisting of roman numerals, returning the corresponding
integer values.
class Roman
def romanToInt(str)
# ...
end
def method_missing(methId)
str = methId.id2name
romanToInt(str)
end
end
|
r = Roman.new
|
r.iv
|
» |
4
|
r.xxiii
|
» |
23
|
r.mm
|
» |
2000
|
|
|
methods
|
obj.methods -> anArray
|
|
Returns a list of the names of methods publicly accessible in
obj. This will include all the methods accessible in obj's
ancestors.
class Klass
|
def kMethod()
|
end
|
end
|
k = Klass.new
|
k.methods[0..9]
|
» |
["kMethod", "dup", "eql?", "protected_methods", "==", "frozen?", "===", "respond_to?", "class", "kind_of?"]
|
k.methods.length
|
» |
38
|
|
|
nil?
|
obj.nil? -> true or false
|
|
All objects except nil return false.
|
|
private_methods
|
obj.private_methods
-> anArray
|
|
Returns a list of private methods accessible within obj. This
will include the private methods in obj's ancestors, along
with any mixed-in module functions.
|
|
protected_methods
|
obj.protected_methods
-> anArray
|
|
Returns the list of protected methods accessible to obj.
|
|
public_methods
|
obj.public_methods -> anArray
|
|
Synonym for
Object#methods
.
|
|
respond_to?
|
obj.respond_to?( aSymbol,
includePriv=false )
-> true or false
|
|
Returns true if obj responds to the given
method. Private methods are included in the search only if the
optional second parameter evaluates to true.
|
|
send
|
obj.send( aSymbol
[, args
]*
) -> anObject
|
|
Invokes the method identified by aSymbol, passing it any
arguments specified. You can use __send__ if the
name send clashes with an existing method in obj.
class Klass
|
def hello(*args)
|
"Hello " + args.join(' ')
|
end
|
end
|
k = Klass.new
|
k.send :hello, "gentle", "readers"
|
» |
"Hello gentle readers"
|
|
|
singleton_methods
|
obj.singleton_methods
-> anArray
|
|
Returns an array of the names of singleton methods for obj.
class Klass
|
def Klass.classMethod
|
end
|
end
|
k = Klass.new
|
def k.sm()
|
end
|
Klass.singleton_methods
|
» |
["classMethod"]
|
k.singleton_methods
|
» |
["sm"]
|
|
|
taint
|
obj.taint -> obj
|
|
Marks obj as tainted
(see Chapter 20, which begins on page 253).
|
|
tainted?
|
obj.tainted? -> true or false
|
|
Returns true if the object is tainted.
|
|
to_a
|
obj.to_a -> anArray
|
|
Returns an array representation of obj. For
objects of class Object and others that don't explicitly
override the method, the return value is an array containing self.
self.to_a
|
» |
[main]
|
"hello".to_a
|
» |
["hello"]
|
Time.new.to_a
|
» |
[15, 18, 0, 9, 6, 2002, 0, 160, true, "CDT"]
|
|
|
to_s
|
obj.to_s -> aString
|
|
Returns a string representing obj. The default to_s
prints the object's class and an encoding of the object id. As a
special case, the top-level object that is the initial execution
context of Ruby programs returns ``main.''
|
|
type
|
obj.type -> aClass
|
|
Returns the class of obj.
|
|
untaint
|
obj.untaint -> obj
|
|
Removes the taint from obj.
|
