Returns an array of all modules used in the current scope. The ordering of modules in the resulting array is not defined.
module A refine Object do end end module B refine Object do end end using A using B p Module.used_modules
produces:
[B, A]
Returns the list of modules included or prepended in mod or one of mod’s ancestors.
module Sub end module Mixin prepend Sub end module Outer include Mixin end Mixin.included_modules #=> [Sub] Outer.included_modules #=> [Sub, Mixin]
Creates instance variables and corresponding methods that return the value of each instance variable. Equivalent to calling “attr
:name” on each name in turn. String
arguments are converted to symbols. Returns an array of defined method names as symbols.
Evaluates the given block in the context of the class/module. The method defined in the block will belong to the receiver. Any arguments passed to the method will be passed to the block. This can be used if the block needs to access instance variables.
class Thing end Thing.class_exec{ def hello() "Hello there!" end } puts Thing.new.hello()
produces:
Hello there!
Evaluates the string or block in the context of mod, except that when a block is given, constant/class variable lookup is not affected. This can be used to add methods to a class. module_eval
returns the result of evaluating its argument. The optional filename and lineno parameters set the text for error messages.
class Thing end a = %q{def hello() "Hello there!" end} Thing.module_eval(a) puts Thing.new.hello() Thing.module_eval("invalid code", "dummy", 123)
produces:
Hello there! dummy:123:in `module_eval': undefined local variable or method `code' for Thing:Class
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?
.
Equivalent to Date#-
with argument n
.
Equivalent to <<
with argument n * 12
.
Erases the screen at the cursor corresponding to mode
. mode
may be either: 0: after cursor 1: before and cursor 2: entire screen
You must require ‘io/console’ to use this method.
Clears the entire screen and moves the cursor top-left corner.
You must require ‘io/console’ to use this method.
Waits until IO
is readable and returns a truthy value, or a falsy value when times out. Returns a truthy value immediately when buffered data is available.
You must require ‘io/wait’ to use this method.
Closes the stream for reading if open for reading; returns nil
. See Open and Closed Streams.
If the stream was opened by IO.popen
and is also closed for writing, sets global variable $?
(child exit status).
Example:
IO.popen('ruby', 'r+') do |pipe| puts pipe.closed? pipe.close_write puts pipe.closed? pipe.close_read puts $? puts pipe.closed? end
Output:
false false pid 14748 exit 0 true
Related: IO#close
, IO#close_write
, IO#closed?
.
Returns a hash representing named captures of self
(see Named Captures):
Each key is the name of a named capture.
Each value is an array of integer indexes for that named capture.
Examples:
/(?<foo>.)(?<bar>.)/.named_captures # => {"foo"=>[1], "bar"=>[2]} /(?<foo>.)(?<foo>.)/.named_captures # => {"foo"=>[1, 2]} /(.)(.)/.named_captures # => {}
Disallows further read using shutdown system call.
s1, s2 = UNIXSocket.pair s1.close_read s2.puts #=> Broken pipe (Errno::EPIPE)
Returns an Addrinfo
object for local address obtained by getsockname.
Note that addrinfo.protocol is filled by 0.
TCPSocket.open("www.ruby-lang.org", 80) {|s| p s.local_address #=> #<Addrinfo: 192.168.0.129:36873 TCP> } TCPServer.open("127.0.0.1", 1512) {|serv| p serv.local_address #=> #<Addrinfo: 127.0.0.1:1512 TCP> }
Returns the IP address as a string.
Addrinfo.tcp("127.0.0.1", 80).ip_address #=> "127.0.0.1" Addrinfo.tcp("::1", 80).ip_address #=> "::1"
Example
UNIXServer.open("/tmp/sock") {|serv| UNIXSocket.open("/tmp/sock") {|c| s = serv.accept c.send_io STDOUT stdout = s.recv_io p STDOUT.fileno #=> 1 p stdout.fileno #=> 7 stdout.puts "hello" # outputs "hello\n" to standard output. } }
klass will determine the class of io returned (using the IO.for_fd
singleton method or similar). If klass is nil
, an integer file descriptor is returned.
mode is the same as the argument passed to IO.for_fd
Closes self
for reading; closed-write setting remains unchanged.
Raises IOError
if reading is attempted.
Related: StringIO#close
, StringIO#close_write
.
Returns true
if self
is closed for reading, false
otherwise.
Returns the substring that precedes the matched substring from the most recent match attempt if it was successful, or nil
otherwise; see [Basic Match Values]:
scanner = StringScanner.new('foobarbaz') scanner.pre_match # => nil scanner.pos = 3 scanner.exist?(/baz/) # => 6 scanner.pre_match # => "foobar" # Substring of entire string, not just target string. scanner.exist?(/nope/) # => nil scanner.pre_match # => nil