Use Addrinfo.getaddrinfo instead. This method is deprecated for the following reasons:
The 3rd element of the result is the address family of the first address. The address families of the rest of the addresses are not returned.
gethostbyname() may take a long time and it may block other threads. (GVL cannot be released since gethostbyname() is not thread safe.)
This method uses gethostbyname() function already removed from POSIX.
This method lookups host information by hostname.
TCPSocket.gethostbyname("localhost") #=> ["localhost", ["hal"], 2, "127.0.0.1"]
Appends the given string to the underlying buffer string. The stream must be opened for writing. If the argument is not a string, it will be converted to a string using to_s. Returns the number of bytes written. See IO#write.
Truncates the buffer string to at most integer bytes. The stream must be opened for writing.
Attempts to skip over the given pattern beginning with the scan pointer. If it matches, the scan pointer is advanced to the end of the match, and the length of the match is returned. Otherwise, nil is returned.
It’s similar to scan, but without returning the matched string.
s = StringScanner.new('test string') p s.skip(/\w+/) # -> 4 p s.skip(/\w+/) # -> nil p s.skip(/\s+/) # -> 1 p s.skip("st") # -> 2 p s.skip(/\w+/) # -> 4 p s.skip(/./) # -> nil
Looks ahead to see if the pattern exists anywhere in the string, without advancing the scan pointer. This predicates whether a scan_until will return a value.
s = StringScanner.new('test string') s.exist? /s/ # -> 3 s.scan /test/ # -> "test" s.exist? /s/ # -> 2 s.exist? /e/ # -> nil
Returns true if and only if there is more data in the string. See eos?. This method is obsolete; use eos? instead.
s = StringScanner.new('test string') # These two are opposites s.eos? # => false s.rest? # => true
Returns the “rest” of the string (i.e. everything after the scan pointer). If there is no more data (eos? = true), it returns "".
s.restsize is equivalent to s.rest_size. This method is obsolete; use rest_size instead.
Associates the given value with the given key; returns value.
If the given key exists, replaces its value with the given value; the ordering is not affected (see Entry Order):
h = {foo: 0, bar: 1} h[:foo] = 2 # => 2 h.store(:bar, 3) # => 3 h # => {:foo=>2, :bar=>3}
If key does not exist, adds the key and value; the new entry is last in the order (see Entry Order):
h = {foo: 0, bar: 1} h[:baz] = 2 # => 2 h.store(:bat, 3) # => 3 h # => {:foo=>0, :bar=>1, :baz=>2, :bat=>3}
Creates, updates, or deletes the named environment variable, returning the value. Both name and value may be instances of String. See Valid Names and Values.
If the named environment variable does not exist:
If value is nil, does nothing.
ENV.clear ENV['foo'] = nil # => nil ENV.include?('foo') # => false ENV.store('bar', nil) # => nil ENV.include?('bar') # => false
If value is not nil, creates the environment variable with name and value:
# Create 'foo' using ENV.[]=. ENV['foo'] = '0' # => '0' ENV['foo'] # => '0' # Create 'bar' using ENV.store. ENV.store('bar', '1') # => '1' ENV['bar'] # => '1'
If the named environment variable exists:
If value is not nil, updates the environment variable with value value:
# Update 'foo' using ENV.[]=. ENV['foo'] = '2' # => '2' ENV['foo'] # => '2' # Update 'bar' using ENV.store. ENV.store('bar', '3') # => '3' ENV['bar'] # => '3'
If value is nil, deletes the environment variable:
# Delete 'foo' using ENV.[]=. ENV['foo'] = nil # => nil ENV.include?('foo') # => false # Delete 'bar' using ENV.store. ENV.store('bar', nil) # => nil ENV.include?('bar') # => false
Raises an exception if name or value is invalid. See Invalid Names and Values.
Writes string if inplace mode.
Writes the given objects to the stream; returns nil. Appends the output record separator $OUTPUT_RECORD_SEPARATOR ($\), if it is not nil. See Line IO.
With argument objects given, for each object:
Converts via its method to_s if not a string.
Writes to the stream.
If not the last object, writes the output field separator $OUTPUT_FIELD_SEPARATOR ($,) if it is not nil.
With default separators:
f = File.open('t.tmp', 'w+') objects = [0, 0.0, Rational(0, 1), Complex(0, 0), :zero, 'zero'] p $OUTPUT_RECORD_SEPARATOR p $OUTPUT_FIELD_SEPARATOR f.print(*objects) f.rewind p f.read f.close
Output:
nil nil "00.00/10+0izerozero"
With specified separators:
$\ = "\n" $, = ',' f.rewind f.print(*objects) f.rewind p f.read
Output:
"0,0.0,0/1,0+0i,zero,zero\n"
With no argument given, writes the content of $_ (which is usually the most recent user input):
f = File.open('t.tmp', 'w+') gets # Sets $_ to the most recent user input. f.print f.close
Formats and writes objects to the stream.
For details on format_string, see Format Specifications.
Sets the current file to the next file in ARGV. If there aren’t any more files it has no effect.
For example:
$ ruby argf.rb foo bar ARGF.filename #=> "foo" ARGF.skip ARGF.filename #=> "bar"
Creates or retrieves cached CSV objects. For arguments and options, see CSV.new.
This API is not Ractor-safe.
With no block given, returns a CSV object.
The first call to instance creates and caches a CSV object:
s0 = 's0' csv0 = CSV.instance(s0) csv0.class # => CSV
Subsequent calls to instance with that same string or io retrieve that same cached object:
csv1 = CSV.instance(s0) csv1.class # => CSV csv1.equal?(csv0) # => true # Same CSV object
A subsequent call to instance with a different string or io creates and caches a different CSV object.
s1 = 's1' csv2 = CSV.instance(s1) csv2.equal?(csv0) # => false # Different CSV object
All the cached objects remains available:
csv3 = CSV.instance(s0) csv3.equal?(csv0) # true # Same CSV object csv4 = CSV.instance(s1) csv4.equal?(csv2) # true # Same CSV object
When a block is given, calls the block with the created or retrieved CSV object; returns the block’s return value:
CSV.instance(s0) {|csv| :foo } # => :foo
Sets the ordering; see Ordering; returns the new ordering.
If the given ordering is PERMUTE and environment variable POSIXLY_CORRECT is defined, sets the ordering to REQUIRE_ORDER; otherwise sets the ordering to ordering:
options = GetoptLong.new options.ordering == GetoptLong::PERMUTE # => true options.ordering = GetoptLong::RETURN_IN_ORDER options.ordering == GetoptLong::RETURN_IN_ORDER # => true ENV['POSIXLY_CORRECT'] = 'true' options.ordering = GetoptLong::PERMUTE options.ordering == GetoptLong::REQUIRE_ORDER # => true
Raises an exception if ordering is invalid.
Returns true if the ipaddr is an IPv4 address.
Returns true if the ipaddr is an IPv6 address.
Returns true if the ipaddr is a private address. IPv4 addresses in 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16 as defined in RFC 1918 and IPv6 Unique Local Addresses in fc00::/7 as defined in RFC 4193 are considered private. Private IPv4 addresses in the IPv4-mapped IPv6 address range are also considered private.
Puts option summary into to and returns to. Yields each line if a block is given.
to
Output destination, which must have method <<. Defaults to [].
width
Width of left side, defaults to @summary_width.
max
Maximum length allowed for left side, defaults to width - 1.
indent
Indentation, defaults to @summary_indent.
Increases left margin after newline with indent for line breaks added in the block.
Opens a transaction block for the store. See Transactions.
With argument read_only as false, the block may both read from and write to the store.
With argument read_only as true, the block may not include calls to transaction, []=, or delete.
Raises an exception if called within a transaction block.
Returns the number of mandatory arguments. If the block is declared to take no arguments, returns 0. If the block is known to take exactly n arguments, returns n. If the block has optional arguments, returns -n-1, where n is the number of mandatory arguments, with the exception for blocks that are not lambdas and have only a finite number of optional arguments; in this latter case, returns n. Keyword arguments will be considered as a single additional argument, that argument being mandatory if any keyword argument is mandatory. A proc with no argument declarations is the same as a block declaring || as its arguments.
proc {}.arity #=> 0 proc { || }.arity #=> 0 proc { |a| }.arity #=> 1 proc { |a, b| }.arity #=> 2 proc { |a, b, c| }.arity #=> 3 proc { |*a| }.arity #=> -1 proc { |a, *b| }.arity #=> -2 proc { |a, *b, c| }.arity #=> -3 proc { |x:, y:, z:0| }.arity #=> 1 proc { |*a, x:, y:0| }.arity #=> -2 proc { |a=0| }.arity #=> 0 lambda { |a=0| }.arity #=> -1 proc { |a=0, b| }.arity #=> 1 lambda { |a=0, b| }.arity #=> -2 proc { |a=0, b=0| }.arity #=> 0 lambda { |a=0, b=0| }.arity #=> -1 proc { |a, b=0| }.arity #=> 1 lambda { |a, b=0| }.arity #=> -2 proc { |(a, b), c=0| }.arity #=> 1 lambda { |(a, b), c=0| }.arity #=> -2 proc { |a, x:0, y:0| }.arity #=> 1 lambda { |a, x:0, y:0| }.arity #=> -2