returns “type/subtype” which is MIME Content-Type. It is downcased for canonicalization. Content-Type parameters are stripped.
Returns a list of encodings in Content-Encoding field as an array of strings.
The encodings are downcased for canonicalization.
Creates an unsigned certificate for subject
and key
. The lifetime of the key is from the current time to age
which defaults to one year.
The extensions
restrict the key to the indicated uses.
Displays an error statement
to the error output location. Asks a question
if given.
Same as Enumerator#with_index(0)
, i.e. there is no starting offset.
If no block is given, a new Enumerator
is returned that includes the index.
Iterates the given block for each element with an arbitrary object, obj
, and returns obj
If no block is given, returns a new Enumerator
.
to_three = Enumerator.new do |y| 3.times do |x| y << x end end to_three_with_string = to_three.with_object("foo") to_three_with_string.each do |x,string| puts "#{string}: #{x}" end # => foo: 0 # => foo: 1 # => foo: 2
Returns the value of the given instance variable, or nil if the instance variable is not set. The @
part of the variable name should be included for regular instance variables. Throws a NameError
exception if the supplied symbol is not valid as an instance variable name. String
arguments are converted to symbols.
class Fred def initialize(p1, p2) @a, @b = p1, p2 end end fred = Fred.new('cat', 99) fred.instance_variable_get(:@a) #=> "cat" fred.instance_variable_get("@b") #=> 99
Sets the instance variable named by symbol to the given object. This may circumvent the encapsulation intended by the author of the class, so it should be used with care. The variable does not have to exist prior to this call. If the instance variable name is passed as a string, that string is converted to a symbol.
class Fred def initialize(p1, p2) @a, @b = p1, p2 end end fred = Fred.new('cat', 99) fred.instance_variable_set(:@a, 'dog') #=> "dog" fred.instance_variable_set(:@c, 'cat') #=> "cat" fred.inspect #=> "#<Fred:0x401b3da8 @a=\"dog\", @b=99, @c=\"cat\">"
Returns true
if the given instance variable is defined in obj. String
arguments are converted to symbols.
class Fred def initialize(p1, p2) @a, @b = p1, p2 end end fred = Fred.new('cat', 99) fred.instance_variable_defined?(:@a) #=> true fred.instance_variable_defined?("@b") #=> true fred.instance_variable_defined?("@c") #=> false
Removes the named instance variable from obj, returning that variable’s value. String
arguments are converted to symbols.
class Dummy attr_reader :var def initialize @var = 99 end def remove remove_instance_variable(:@var) end end d = Dummy.new d.var #=> 99 d.remove #=> 99 d.var #=> nil
Defines a public singleton method in the receiver. The method parameter can be a Proc
, a Method
or an UnboundMethod
object. If a block is specified, it is used as the method body. If a block or a method has parameters, they’re used as method parameters.
class A class << self def class_name to_s end end end A.define_singleton_method(:who_am_i) do "I am: #{class_name}" end A.who_am_i # ==> "I am: A" guy = "Bob" guy.define_singleton_method(:hello) { "#{self}: Hello there!" } guy.hello #=> "Bob: Hello there!" chris = "Chris" chris.define_singleton_method(:greet) {|greeting| "#{greeting}, I'm Chris!" } chris.greet("Hi") #=> "Hi, I'm Chris!"
DO NOT USE THIS DIRECTLY.
Hook method to return whether the obj can respond to id method or not.
When the method name parameter is given as a string, the string is converted to a symbol.
See respond_to?
, and the example of BasicObject
.
Sets the temporary name of the module. This name is reflected in introspection of the module and the values that are related to it, such as instances, constants, and methods.
The name should be nil
or non-empty string that is not a valid constant name (to avoid confusing between permanent and temporary names).
The method can be useful to distinguish dynamically generated classes and modules without assigning them to constants.
If the module is given a permanent name by assigning it to a constant, the temporary name is discarded. A temporary name can’t be assigned to modules that have a permanent name.
If the given name is nil
, the module becomes anonymous again.
Example:
m = Module.new # => #<Module:0x0000000102c68f38> m.name #=> nil m.set_temporary_name("fake_name") # => fake_name m.name #=> "fake_name" m.set_temporary_name(nil) # => #<Module:0x0000000102c68f38> m.name #=> nil c = Class.new c.set_temporary_name("MyClass(with description)") c.new # => #<MyClass(with description):0x0....> c::M = m c::M.name #=> "MyClass(with description)::M" # Assigning to a constant replaces the name with a permanent one C = c C.name #=> "C" C::M.name #=> "C::M" c.new # => #<C:0x0....>
Removes the named class variable from the receiver, returning that variable’s value.
class Example @@var = 99 puts remove_class_variable(:@@var) p(defined? @@var) end
produces:
99 nil
Returns the value of the given class variable (or throws a NameError
exception). The @@
part of the variable name should be included for regular class variables. String
arguments are converted to symbols.
class Fred @@foo = 99 end Fred.class_variable_get(:@@foo) #=> 99
Sets the class variable named by symbol to the given object. If the class variable name is passed as a string, that string is converted to a symbol.
class Fred @@foo = 99 def foo @@foo end end Fred.class_variable_set(:@@foo, 101) #=> 101 Fred.new.foo #=> 101
Returns true
if the given class variable is defined in obj. String
arguments are converted to symbols.
class Fred @@foo = 99 end Fred.class_variable_defined?(:@@foo) #=> true Fred.class_variable_defined?(:@@bar) #=> false
Returns true
if the stream will be closed on exec, false
otherwise:
f = File.open('t.txt') f.close_on_exec? # => true f.close_on_exec = false f.close_on_exec? # => false f.close
Sets a close-on-exec flag.
f = File.open(File::NULL) f.close_on_exec = true system("cat", "/proc/self/fd/#{f.fileno}") # cat: /proc/self/fd/3: No such file or directory f.closed? #=> false
Ruby sets close-on-exec flags of all file descriptors by default since Ruby 2.0.0. So you don’t need to set by yourself. Also, unsetting a close-on-exec flag can cause file descriptor leak if another thread use fork() and exec() (via system() method for example). If you really needs file descriptor inheritance to child process, use spawn()‘s argument such as fd=>fd.
for compatibility