Returns zero.
Returns the denominator (always positive).
Returns 0 if self is positive, Math::PI otherwise.
Returns self truncated (toward zero) to a precision of ndigits decimal digits.
When ndigits is positive, returns a float with ndigits digits after the decimal point (as available):
f = 12345.6789 f.truncate(1) # => 12345.6 f.truncate(3) # => 12345.678 f = -12345.6789 f.truncate(1) # => -12345.6 f.truncate(3) # => -12345.678
When ndigits is negative, returns an integer with at least ndigits.abs trailing zeros:
f = 12345.6789 f.truncate(0) # => 12345 f.truncate(-3) # => 12000 f = -12345.6789 f.truncate(0) # => -12345 f.truncate(-3) # => -12000
Note that the limited precision of floating-point arithmetic may lead to surprising results:
(0.3 / 0.1).truncate #=> 2 (!)
Related: Float#round.
Returns true if self is not Infinity, -Infinity, or NaN, false otherwise:
f = 2.0 # => 2.0 f.finite? # => true f = 1.0/0.0 # => Infinity f.finite? # => false f = -1.0/0.0 # => -Infinity f.finite? # => false f = 0.0/0.0 # => NaN f.finite? # => false
Returns a string containing a representation of self; depending of the value of self, the string representation may contain:
A fixed-point number.
A number in “scientific notation” (containing an exponent).
‘Infinity’.
‘-Infinity’.
‘NaN’ (indicating not-a-number).
3.14.to_s # => “3.14” (10.1**50).to_s # => “1.644631821843879e+50” (10.1**500).to_s # => “Infinity” (-10.1**500).to_s # => “-Infinity” (0.0/0.0).to_s # => “NaN”
Returns the denominator (always positive). The result is machine dependent.
See also Float#numerator.
Returns a copy of the storage hash for the fiber. The method can only be called on the Fiber.current.
Sets the storage hash for the fiber. This feature is experimental and may change in the future. The method can only be called on the Fiber.current.
You should be careful about using this method as you may inadvertently clear important fiber-storage state. You should mostly prefer to assign specific keys in the storage using Fiber::[]=.
You can also use Fiber.new(storage: nil) to create a fiber with an empty storage.
Example:
while request = request_queue.pop # Reset the per-request state: Fiber.current.storage = nil handle_request(request) end
Returns the current execution stack of the fiber. start, count and end allow to select only parts of the backtrace.
def level3 Fiber.yield end def level2 level3 end def level1 level2 end f = Fiber.new { level1 } # It is empty before the fiber started f.backtrace #=> [] f.resume f.backtrace #=> ["test.rb:2:in `yield'", "test.rb:2:in `level3'", "test.rb:6:in `level2'", "test.rb:10:in `level1'", "test.rb:13:in `block in <main>'"] p f.backtrace(1) # start from the item 1 #=> ["test.rb:2:in `level3'", "test.rb:6:in `level2'", "test.rb:10:in `level1'", "test.rb:13:in `block in <main>'"] p f.backtrace(2, 2) # start from item 2, take 2 #=> ["test.rb:6:in `level2'", "test.rb:10:in `level1'"] p f.backtrace(1..3) # take items from 1 to 3 #=> ["test.rb:2:in `level3'", "test.rb:6:in `level2'", "test.rb:10:in `level1'"] f.resume # It is nil after the fiber is finished f.backtrace #=> nil
Transfer control to another fiber, resuming it from where it last stopped or starting it if it was not resumed before. The calling fiber will be suspended much like in a call to Fiber.yield.
The fiber which receives the transfer call treats it much like a resume call. Arguments passed to transfer are treated like those passed to resume.
The two style of control passing to and from fiber (one is resume and Fiber::yield, another is transfer to and from fiber) can’t be freely mixed.
If the Fiber’s lifecycle had started with transfer, it will never be able to yield or be resumed control passing, only finish or transfer back. (It still can resume other fibers that are allowed to be resumed.)
If the Fiber’s lifecycle had started with resume, it can yield or transfer to another Fiber, but can receive control back only the way compatible with the way it was given away: if it had transferred, it only can be transferred back, and if it had yielded, it only can be resumed back. After that, it again can transfer or yield.
If those rules are broken FiberError is raised.
For an individual Fiber design, yield/resume is easier to use (the Fiber just gives away control, it doesn’t need to think about who the control is given to), while transfer is more flexible for complex cases, allowing to build arbitrary graphs of Fibers dependent on each other.
Example:
manager = nil # For local var to be visible inside worker block # This fiber would be started with transfer # It can't yield, and can't be resumed worker = Fiber.new { |work| puts "Worker: starts" puts "Worker: Performed #{work.inspect}, transferring back" # Fiber.yield # this would raise FiberError: attempt to yield on a not resumed fiber # manager.resume # this would raise FiberError: attempt to resume a resumed fiber (double resume) manager.transfer(work.capitalize) } # This fiber would be started with resume # It can yield or transfer, and can be transferred # back or resumed manager = Fiber.new { puts "Manager: starts" puts "Manager: transferring 'something' to worker" result = worker.transfer('something') puts "Manager: worker returned #{result.inspect}" # worker.resume # this would raise FiberError: attempt to resume a transferring fiber Fiber.yield # this is OK, the fiber transferred from and to, now it can yield puts "Manager: finished" } puts "Starting the manager" manager.resume puts "Resuming the manager" # manager.transfer # this would raise FiberError: attempt to transfer to a yielding fiber manager.resume
produces
Starting the manager Manager: starts Manager: transferring 'something' to worker Worker: starts Worker: Performed "something", transferring back Manager: worker returned "Something" Resuming the manager Manager: finished
Sets the position in self to zero; see Dir As Stream-Like:
dir = Dir.new('example') dir.read # => "." dir.read # => ".." dir.pos # => 2 dir.rewind # => #<Dir:example> dir.pos # => 0
Removes the directory at dirpath from the underlying file system:
Dir.rmdir('foo') # => 0
Raises an exception if the directory is not empty.
Returns whether dirpath is a directory in the underlying file system:
Dir.exist?('/example') # => true Dir.exist?('/nosuch') # => false Dir.exist?('/example/main.rb') # => false
Same as File.directory?.
Returns a File::Stat object for the file at filepath (see File::Stat):
File.stat('t.txt').class # => File::Stat
Like File::stat, but does not follow the last symbolic link; instead, returns a File::Stat object for the link itself.
File.symlink('t.txt', 'symlink') File.stat('symlink').size # => 47 File.lstat('symlink').size # => 5
Creates a new name for an existing file using a hard link. Will not overwrite new_name if it already exists (raising a subclass of SystemCallError). Not available on all platforms.
File.link("testfile", ".testfile") #=> 0 IO.readlines(".testfile")[0] #=> "This is line one\n"
Creates a symbolic link called new_name for the existing file old_name. Raises a NotImplemented exception on platforms that do not support symbolic links.
File.symlink("testfile", "link2test") #=> 0
Returns the name of the file referenced by the given link. Not available on all platforms.
File.symlink("testfile", "link2test") #=> 0 File.readlink("link2test") #=> "testfile"
Deletes the named files, returning the number of names passed as arguments. Raises an exception on any error. Since the underlying implementation relies on the unlink(2) system call, the type of exception raised depends on its error type (see linux.die.net/man/2/unlink) and has the form of e.g. Errno::ENOENT.
See also Dir::rmdir.
Truncates the file file_name to be at most integer bytes long. Not available on all platforms.
f = File.new("out", "w") f.write("1234567890") #=> 10 f.close #=> nil File.truncate("out", 5) #=> 0 File.size("out") #=> 5
Returns a new string formed by joining the strings using "/".
File.join("usr", "mail", "gumby") #=> "usr/mail/gumby"
Like File#stat, but does not follow the last symbolic link; instead, returns a File::Stat object for the link itself:
File.symlink('t.txt', 'symlink') f = File.new('symlink') f.stat.size # => 47 f.lstat.size # => 11