Returns true for dummy encodings. A dummy encoding is an encoding for which character handling is not properly implemented. It is used for stateful encodings.
Encoding::ISO_2022_JP.dummy? #=> true Encoding::UTF_8.dummy? #=> false
Returns the return value of the iterator.
o = Object.new def o.each yield 1 yield 2 yield 3 100 end e = o.to_enum puts e.next #=> 1 puts e.next #=> 2 puts e.next #=> 3 begin e.next rescue StopIteration => ex puts ex.result #=> 100 end
The primary interface to this library. Use to setup delegation when defining your class.
class MyClass < DelegateClass(ClassToDelegateTo) # Step 1 def initialize super(obj_of_ClassToDelegateTo) # Step 2 end end
or:
MyClass = DelegateClass(ClassToDelegateTo) do # Step 1 def initialize super(obj_of_ClassToDelegateTo) # Step 2 end end
Here’s a sample of use from Tempfile which is really a File object with a few special rules about storage location and when the File should be deleted. That makes for an almost textbook perfect example of how to use delegation.
class Tempfile < DelegateClass(File) # constant and class member data initialization... def initialize(basename, tmpdir=Dir::tmpdir) # build up file path/name in var tmpname... @tmpfile = File.open(tmpname, File::RDWR|File::CREAT|File::EXCL, 0600) # ... super(@tmpfile) # below this point, all methods of File are supported... end # ... end
Produces a shallow copy of obj—the instance variables of obj are copied, but not the objects they reference.
This method may have class-specific behavior. If so, that behavior will be documented under the #initialize_copy method of the class.
In general, clone and dup may have different semantics in descendant classes. While clone is used to duplicate an object, including its internal state, dup typically uses the class of the descendant object to create the new instance.
When using dup, any modules that the object has been extended with will not be copied.
class Klass attr_accessor :str end module Foo def foo; 'foo'; end end s1 = Klass.new #=> #<Klass:0x401b3a38> s1.extend(Foo) #=> #<Klass:0x401b3a38> s1.foo #=> "foo" s2 = s1.clone #=> #<Klass:0x401be280> s2.foo #=> "foo" s3 = s1.dup #=> #<Klass:0x401c1084> s3.foo #=> NoMethodError: undefined method `foo' for #<Klass:0x401c1084>
Returns a list of the names of public and protected methods of obj. This will include all the methods accessible in obj’s ancestors. If the optional parameter is false, it returns an array of obj’s public and protected singleton methods, the array will not include methods in modules included in obj.
class Klass def klass_method() end end k = Klass.new k.methods[0..9] #=> [:klass_method, :nil?, :===, # :==~, :!, :eql? # :hash, :<=>, :class, :singleton_class] k.methods.length #=> 56 k.methods(false) #=> [] def k.singleton_method; end k.methods(false) #=> [:singleton_method] module M123; def m123; end end k.extend M123 k.methods(false) #=> [:singleton_method]
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"
Note that Method implements to_proc method, which means it can be used with iterators.
[ 1, 2, 3 ].each(&method(:puts)) # => prints 3 lines to stdout out = File.open('test.txt', 'w') [ 1, 2, 3 ].each(&out.method(:puts)) # => prints 3 lines to file require 'date' %w[2017-03-01 2017-03-02].collect(&Date.method(:parse)) #=> [#<Date: 2017-03-01 ((2457814j,0s,0n),+0s,2299161j)>, #<Date: 2017-03-02 ((2457815j,0s,0n),+0s,2299161j)>]
Returns true if the given year is a leap year in the proleptic Gregorian calendar, false otherwise:
Date.gregorian_leap?(2000) # => true Date.gregorian_leap?(2001) # => false
Related: Date.julian_leap?.
Returns a new Date object constructed from the present date:
Date.today.to_s # => "2022-07-06"
See argument start.
Returns true if the date is before the date of calendar reform, false otherwise:
(Date.new(1582, 10, 15) - 1).julian? # => true Date.new(1582, 10, 15).julian? # => false
Returns true if the year is a leap year, false otherwise:
Date.new(2000).leap? # => true Date.new(2001).leap? # => false
Equivalent to Date#new_start with argument Date::JULIAN.
Returns the integer file descriptor for the stream:
$stdin.fileno # => 0 $stdout.fileno # => 1 $stderr.fileno # => 2 File.open('t.txt').fileno # => 10 f.close
Alias for Regexp.new
Removes all elements and returns self.
set = Set[1, 'c', :s] #=> #<Set: {1, "c", :s}> set.clear #=> #<Set: {}> set #=> #<Set: {}>
Deletes the given object from the set and returns self. Use subtract to delete many items at once.
Deletes the given object from the set and returns self. If the object is not in the set, returns nil.
Returns the number of members.
Customer = Struct.new(:name, :address, :zip) joe = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345) joe.size #=> 3
Equivalent to self.to_s.length; see String#length.
Returns clean pathname of self with consecutive slashes and useless dots removed. The filesystem is not accessed.
If consider_symlink is true, then a more conservative algorithm is used to avoid breaking symbolic linkages. This may retain more .. entries than absolutely necessary, but without accessing the filesystem, this can’t be avoided.
See Pathname#realpath.
Removes a file or directory, using File.unlink if self is a file, or Dir.unlink as necessary.