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
Execute the provided block, but preserve the precision limit
BigDecimal.limit(100) puts BigDecimal.limit BigDecimal.save_limit do BigDecimal.limit(200) puts BigDecimal.limit end puts BigDecimal.limit
Returns true if the given year is a leap year of the proleptic Gregorian calendar.
Date.gregorian_leap?(1900) #=> false Date.gregorian_leap?(2000) #=> true
This method is equivalent to d - n.
This method is equivalent to d << (n * 12).
Date.new(2001,2,3).prev_year #=> #<Date: 2000-02-03 ...> Date.new(2008,2,29).prev_year #=> #<Date: 2007-02-28 ...> Date.new(2008,2,29).prev_year(4) #=> #<Date: 2004-02-29 ...>
See also Date#<<
.
Waits until IO
is readable and returns true
, or false
when times out. Returns true
immediately when buffered data is available.
Closes the read end of a duplex I/O stream (i.e., one that contains both a read and a write stream, such as a pipe). Will raise an IOError
if the stream is not duplexed.
f = IO.popen("/bin/sh","r+") f.close_read f.readlines
produces:
prog.rb:3:in `readlines': not opened for reading (IOError) from prog.rb:3
Calling this method on closed IO
object is just ignored since Ruby 2.3.
Returns a hash representing information about named captures of rxp.
A key of the hash is a name of the named captures. A value of the hash is an array which is list of indexes of corresponding named captures.
/(?<foo>.)(?<bar>.)/.named_captures #=> {"foo"=>[1], "bar"=>[2]} /(?<foo>.)(?<foo>.)/.named_captures #=> {"foo"=>[1, 2]}
If there are no named captures, an empty hash is returned.
/(.)(.)/.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 the read end of a StringIO
. Will raise an IOError
if the receiver is not readable.
Returns true
if the stream is not readable, false
otherwise.
Returns the pre-match
(in the regular expression sense) of the last scan.s = StringScanner.new('test string') s.scan(/\w+/) # -> "test" s.scan(/\s+/) # -> " " s.pre_match # -> "test" s.post_match # -> "string"
Invokes Release method of Dispatch interface of WIN32OLE
object. You should not use this method because this method exists only for debugging WIN32OLE
. The return value is reference counter of OLE object.