Lookups the IP address of host.
require 'socket' IPSocket.getaddress("localhost") #=> "127.0.0.1" IPSocket.getaddress("ip6-localhost") #=> "::1"
iterates over the list of Addrinfo
objects obtained by Addrinfo.getaddrinfo
.
Addrinfo.foreach(nil, 80) {|x| p x } #=> #<Addrinfo: 127.0.0.1:80 TCP (:80)> # #<Addrinfo: 127.0.0.1:80 UDP (:80)> # #<Addrinfo: [::1]:80 TCP (:80)> # #<Addrinfo: [::1]:80 UDP (:80)>
Receives a message via unixsocket.
maxlen is the maximum number of bytes to receive.
flags should be a bitwise OR of Socket::MSG_* constants.
outbuf will contain only the received data after the method call even if it is not empty at the beginning.
s1 = Socket.new(:UNIX, :DGRAM, 0) s1_ai = Addrinfo.unix("/tmp/sock1") s1.bind(s1_ai) s2 = Socket.new(:UNIX, :DGRAM, 0) s2_ai = Addrinfo.unix("/tmp/sock2") s2.bind(s2_ai) s3 = UNIXSocket.for_fd(s2.fileno) s1.send "a", 0, s2_ai p s3.recvfrom(10) #=> ["a", ["AF_UNIX", "/tmp/sock1"]]
Reinitializes the stream with the given other
(string or StringIO
) and mode
; see IO.new
:
StringIO.open('foo') do |strio| p strio.string strio.reopen('bar') p strio.string other_strio = StringIO.new('baz') strio.reopen(other_strio) p strio.string other_strio.close end
Output:
"foo" "bar" "baz"
Sets the data mode in self
to binary mode; see Data Mode.
Sets the current position and line number to zero; see Position and Line Number.
See IO#read
.
See IO#pread
.
Sets both [byte position] and [character position] to zero, and clears [match values]; returns self
:
scanner = StringScanner.new('foobarbaz') scanner.exist?(/bar/) # => 6 scanner.reset # => #<StringScanner 0/9 @ "fooba..."> put_situation(scanner) # Situation: # pos: 0 # charpos: 0 # rest: "foobarbaz" # rest_size: 9 # => nil match_values_cleared?(scanner) # => true
Returns the array of [captured match values] at indexes (1..)
if the most recent match attempt succeeded, or nil
otherwise:
scanner = StringScanner.new('Fri Dec 12 1975 14:39') scanner.captures # => nil scanner.exist?(/(?<wday>\w+) (?<month>\w+) (?<day>\d+) /) scanner.captures # => ["Fri", "Dec", "12"] scanner.values_at(*0..4) # => ["Fri Dec 12 ", "Fri", "Dec", "12", nil] scanner.exist?(/Fri/) scanner.captures # => [] scanner.scan(/nope/) scanner.captures # => nil
Rebuilds the hash table by recomputing the hash index for each key; returns self
.
The hash table becomes invalid if the hash value of a key has changed after the entry was created. See Modifying an Active Hash Key.
Returns true
if there are no hash entries, false
otherwise:
{}.empty? # => true {foo: 0, bar: 1, baz: 2}.empty? # => false
Returns a new Hash
object whose entries are all those from self
for which the block returns false
or nil
:
h = {foo: 0, bar: 1, baz: 2} h1 = h.reject {|key, value| key.start_with?('b') } h1 # => {foo: 0}
Returns a new Enumerator
if no block given:
h = {foo: 0, bar: 1, baz: 2} e = h.reject # => #<Enumerator: {foo: 0, bar: 1, baz: 2}:reject> h1 = e.each {|key, value| key.start_with?('b') } h1 # => {foo: 0}
Returns self
, whose remaining entries are those for which the block returns false
or nil
:
h = {foo: 0, bar: 1, baz: 2} h.reject! {|key, value| value < 2 } # => {baz: 2}
Returns nil
if no entries are removed.
Returns a new Enumerator
if no block given:
h = {foo: 0, bar: 1, baz: 2} e = h.reject! # => #<Enumerator: {foo: 0, bar: 1, baz: 2}:reject!> e.each {|key, value| key.start_with?('b') } # => {foo: 0}
Returns a new Hash
object with the each key-value pair inverted:
h = {foo: 0, bar: 1, baz: 2} h1 = h.invert h1 # => {0=>:foo, 1=>:bar, 2=>:baz}
Overwrites any repeated new keys: (see Entry Order):
h = {foo: 0, bar: 0, baz: 0} h.invert # => {0=>:baz}
Replaces the entire contents of self
with the contents of other_hash
; returns self
:
h = {foo: 0, bar: 1, baz: 2} h.replace({bat: 3, bam: 4}) # => {bat: 3, bam: 4}
Returns true
if key
is a key in self
, otherwise false
.
Yields each environment variable name and its value as a 2-element Array
. Returns a Hash
whose items are determined by the block. When the block returns a truthy value, the name/value pair is added to the return Hash
; otherwise the pair is ignored:
ENV.replace('foo' => '0', 'bar' => '1', 'baz' => '2') ENV.reject { |name, value| name.start_with?('b') } # => {"foo"=>"0"}
Returns an Enumerator
if no block given:
e = ENV.reject e.each { |name, value| name.start_with?('b') } # => {"foo"=>"0"}
Similar to ENV.delete_if
, but returns nil
if no changes were made.
Yields each environment variable name and its value as a 2-element Array
, deleting each environment variable for which the block returns a truthy value, and returning ENV
(if any deletions) or nil
(if not):
ENV.replace('foo' => '0', 'bar' => '1', 'baz' => '2') ENV.reject! { |name, value| name.start_with?('b') } # => ENV ENV # => {"foo"=>"0"} ENV.reject! { |name, value| name.start_with?('b') } # => nil
Returns an Enumerator
if no block given:
ENV.replace('foo' => '0', 'bar' => '1', 'baz' => '2') e = ENV.reject! # => #<Enumerator: {"bar"=>"1", "baz"=>"2", "foo"=>"0"}:reject!> e.each { |name, value| name.start_with?('b') } # => ENV ENV # => {"foo"=>"0"} e.each { |name, value| name.start_with?('b') } # => nil
Returns a Hash
whose keys are the ENV
values, and whose values are the corresponding ENV
names:
ENV.replace('foo' => '0', 'bar' => '1') ENV.invert # => {"1"=>"bar", "0"=>"foo"}
For a duplicate ENV
value, overwrites the hash entry:
ENV.replace('foo' => '0', 'bar' => '0') ENV.invert # => {"0"=>"foo"}
Note that the order of the ENV
processing is OS-dependent, which means that the order of overwriting is also OS-dependent. See About Ordering.
Replaces the entire content of the environment variables with the name/value pairs in the given hash
; returns ENV
.
Replaces the content of ENV
with the given pairs:
ENV.replace('foo' => '0', 'bar' => '1') # => ENV ENV.to_hash # => {"bar"=>"1", "foo"=>"0"}
Raises an exception if a name or value is invalid (see Invalid Names and Values):
ENV.replace('foo' => '0', :bar => '1') # Raises TypeError (no implicit conversion of Symbol into String) ENV.replace('foo' => '0', 'bar' => 1) # Raises TypeError (no implicit conversion of Integer into String) ENV.to_hash # => {"bar"=>"1", "foo"=>"0"}
Returns true
when there are no environment variables, false
otherwise:
ENV.clear ENV.empty? # => true ENV['foo'] = '0' ENV.empty? # => false