Prepends each string in other_strings to self and returns self:
s = 'foo' s.prepend('bar', 'baz') # => "barbazfoo" s # => "barbazfoo"
Related: String#concat.
Returns self rounded to the nearest value with a precision of ndigits decimal digits.
When ndigits is non-negative, returns a float with ndigits after the decimal point (as available):
f = 12345.6789 f.round(1) # => 12345.7 f.round(3) # => 12345.679 f = -12345.6789 f.round(1) # => -12345.7 f.round(3) # => -12345.679
When ndigits is negative, returns an integer with at least ndigits.abs trailing zeros:
f = 12345.6789 f.round(0) # => 12346 f.round(-3) # => 12000 f = -12345.6789 f.round(0) # => -12346 f.round(-3) # => -12000
If keyword argument half is given, and self is equidistant from the two candidate values, the rounding is according to the given half value:
:up or nil: round away from zero:
2.5.round(half: :up) # => 3 3.5.round(half: :up) # => 4 (-2.5).round(half: :up) # => -3
:down: round toward zero:
2.5.round(half: :down) # => 2 3.5.round(half: :down) # => 3 (-2.5).round(half: :down) # => -2
:even: round toward the candidate whose last nonzero digit is even:
2.5.round(half: :even) # => 2 3.5.round(half: :even) # => 4 (-2.5).round(half: :even) # => -2
Raises and exception if the value for half is invalid.
Related: Float#truncate.
Returns true if self is 0.0, false otherwise.
Forces the fiber to be blocking for the duration of the block. Returns the result of the block.
See the “Non-blocking fibers” section in class docs for details.
Returns true if fiber is blocking and false otherwise. Fiber is non-blocking if it was created via passing blocking: false to Fiber.new, or via Fiber.schedule.
Note that, even if the method returns false, the fiber behaves differently only if Fiber.scheduler is set in the current thread.
See the “Non-blocking fibers” section in class docs for details.
Returns false if the current fiber is non-blocking. Fiber is non-blocking if it was created via passing blocking: false to Fiber.new, or via Fiber.schedule.
If the current Fiber is blocking, the method returns 1. Future developments may allow for situations where larger integers could be returned.
Note that, even if the method returns false, Fiber behaves differently only if Fiber.scheduler is set in the current thread.
See the “Non-blocking fibers” section in class docs for details.
Changes the root directory of the calling process to that specified in dirpath. The new root directory is used for pathnames beginning with '/'. The root directory is inherited by all children of the calling process.
Only a privileged process may call chroot.
See Linux chroot.
Locks or unlocks file self according to the given locking_constant, a bitwise OR of the values in the table below.
Not available on all platforms.
Returns false if File::LOCK_NB is specified and the operation would have blocked; otherwise returns 0.
| Constant | Lock | Effect |
|---|---|---|
File::LOCK_EX |
Exclusive | Only one process may hold an exclusive lock for self at a time. |
File::LOCK_NB |
Non-blocking | No blocking; may be combined with File::LOCK_SH or File::LOCK_EX using the bitwise OR operator |. |
File::LOCK_SH |
Shared | Multiple processes may each hold a shared lock for self at the same time. |
File::LOCK_UN |
Unlock | Remove an existing lock held by this process. |
Example:
# Update a counter using an exclusive lock. # Don't use File::WRONLY because it truncates the file. File.open('counter', File::RDWR | File::CREAT, 0644) do |f| f.flock(File::LOCK_EX) value = f.read.to_i + 1 f.rewind f.write("#{value}\n") f.flush f.truncate(f.pos) end # Read the counter using a shared lock. File.open('counter', 'r') do |f| f.flock(File::LOCK_SH) f.read end
Returns true if the named file exists and has a zero size.
file_name can be an IO object.
Returns true if filepath points to a socket, false otherwise:
require 'socket' File.socket?(Socket.new(:INET, :STREAM)) # => true File.socket?(File.new('t.txt')) # => false
Returns true if filepath points to a block device, false otherwise:
File.blockdev?('/dev/sda1') # => true File.blockdev?(File.new('t.tmp')) # => false
Invokes Module.prepend_features on each parameter in reverse order.
The equivalent of included, but for prepended modules.
module A def self.prepended(mod) puts "#{self} prepended to #{mod}" end end module Enumerable prepend A end # => prints "A prepended to Enumerable"
With no arguments, sets the default visibility for subsequently defined methods to private. With arguments, sets the named methods to have private visibility. String arguments are converted to symbols. An Array of Symbols and/or Strings is also accepted. If a single argument is passed, it is returned. If no argument is passed, nil is returned. If multiple arguments are passed, the arguments are returned as an array.
module Mod def a() end def b() end private def c() end private :a end Mod.private_instance_methods #=> [:a, :c]
Note that to show a private method on RDoc, use :doc:.
Like Time.utc, except that the returned Time object has the local timezone, not the UTC timezone:
# With seven arguments. Time.local(0, 1, 2, 3, 4, 5, 6) # => 0000-01-02 03:04:05.000006 -0600 # With exactly ten arguments. Time.local(0, 1, 2, 3, 4, 5, 6, 7, 8, 9) # => 0005-04-03 02:01:00 -0600
With no argument given:
Returns self if self is a local time.
Otherwise returns a new Time in the user’s local timezone:
t = Time.utc(2000, 1, 1, 20, 15, 1) # => 2000-01-01 20:15:01 UTC t.localtime # => 2000-01-01 14:15:01 -0600
With argument zone given, returns the new Time object created by converting self to the given time zone:
t = Time.utc(2000, 1, 1, 20, 15, 1) # => 2000-01-01 20:15:01 UTC t.localtime("-09:00") # => 2000-01-01 11:15:01 -0900
For forms of argument zone, see Timezone Specifiers.
Returns a new Time object representing the value of self converted to a given timezone; if zone is nil, the local timezone is used:
t = Time.utc(2000) # => 2000-01-01 00:00:00 UTC t.getlocal # => 1999-12-31 18:00:00 -0600 t.getlocal('+12:00') # => 2000-01-01 12:00:00 +1200
For forms of argument zone, see Timezone Specifiers.
Returns a new Time object whose numeric value is that of self, with its seconds value rounded to precision ndigits:
t = Time.utc(2010, 3, 30, 5, 43, 25.123456789r) t # => 2010-03-30 05:43:25.123456789 UTC t.round # => 2010-03-30 05:43:25 UTC t.round(0) # => 2010-03-30 05:43:25 UTC t.round(1) # => 2010-03-30 05:43:25.1 UTC t.round(2) # => 2010-03-30 05:43:25.12 UTC t.round(3) # => 2010-03-30 05:43:25.123 UTC t.round(4) # => 2010-03-30 05:43:25.1235 UTC t = Time.utc(1999, 12,31, 23, 59, 59) t # => 1999-12-31 23:59:59 UTC (t + 0.4).round # => 1999-12-31 23:59:59 UTC (t + 0.49).round # => 1999-12-31 23:59:59 UTC (t + 0.5).round # => 2000-01-01 00:00:00 UTC (t + 1.4).round # => 2000-01-01 00:00:00 UTC (t + 1.49).round # => 2000-01-01 00:00:00 UTC (t + 1.5).round # => 2000-01-01 00:00:01 UTC
Related: Time#ceil, Time#floor.
Returns true if key is pressed. key may be a virtual key code or its name (String or Symbol) with out “VK_” prefix.
This method is Windows only.
You must require ‘io/console’ to use this method.
Returns true if an IO object is in non-blocking mode.
Enables non-blocking mode on a stream when set to true, and blocking mode when set to false.
This method set or clear O_NONBLOCK flag for the file descriptor in ios.
The behavior of most IO methods is not affected by this flag because they retry system calls to complete their task after EAGAIN and partial read/write. (An exception is IO#syswrite which doesn’t retry.)
This method can be used to clear non-blocking mode of standard I/O. Since nonblocking methods (read_nonblock, etc.) set non-blocking mode but they doesn’t clear it, this method is usable as follows.
END { STDOUT.nonblock = false } STDOUT.write_nonblock("foo")
Since the flag is shared across processes and many non-Ruby commands doesn’t expect standard I/O with non-blocking mode, it would be safe to clear the flag before Ruby program exits.
For example following Ruby program leaves STDIN/STDOUT/STDER non-blocking mode. (STDIN, STDOUT and STDERR are connected to a terminal. So making one of them nonblocking-mode effects other two.) Thus cat command try to read from standard input and it causes “Resource temporarily unavailable” error (EAGAIN).
% ruby -e '
STDOUT.write_nonblock("foo\n")'; cat
foo
cat: -: Resource temporarily unavailable
Clearing the flag makes the behavior of cat command normal. (cat command waits input from standard input.)
% ruby -rio/nonblock -e '
END { STDOUT.nonblock = false }
STDOUT.write_nonblock("foo")
'; cat
foo
Yields self in non-blocking mode.
When false is given as an argument, self is yielded in blocking mode. The original mode is restored after the block is executed.
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.
Behaves like IO#readpartial, except that it:
Reads at the given offset (in bytes).
Disregards, and does not modify, the stream’s position (see Position).
Bypasses any user space buffering in the stream.
Because this method does not disturb the stream’s state (its position, in particular), pread allows multiple threads and processes to use the same IO object for reading at various offsets.
f = File.open('t.txt') f.read # => "First line\nSecond line\n\nFourth line\nFifth line\n" f.pos # => 52 # Read 12 bytes at offset 0. f.pread(12, 0) # => "First line\n" # Read 9 bytes at offset 8. f.pread(9, 8) # => "ne\nSecon" f.close
Not available on some platforms.