Results for: "Array"

NilClass#rationalize

Returns zero as a rational. The optional argument eps is always ignored.

Numeric#arg

Returns 0 if the value is positive, pi otherwise.

String#clear

Removes the contents of self:

s = 'foo' # => "foo"
s.clear   # => ""

String#chars

Returns an array of the characters in self:

'hello'.chars     # => ["h", "e", "l", "l", "o"]
'тест'.chars      # => ["т", "е", "с", "т"]
'こんにちは'.chars # => ["こ", "ん", "に", "ち", "は"]

String#partition

Returns a 3-element array of substrings of self.

Matches a pattern against self, scanning from the beginning. The pattern is:

string_or_regexp itself, if it is a Regexp.
Regexp.quote(string_or_regexp), if string_or_regexp is a string.

If the pattern is matched, returns pre-match, first-match, post-match:

'hello'.partition('l')      # => ["he", "l", "lo"]
'hello'.partition('ll')     # => ["he", "ll", "o"]
'hello'.partition('h')      # => ["", "h", "ello"]
'hello'.partition('o')      # => ["hell", "o", ""]
'hello'.partition(/l+/)     #=> ["he", "ll", "o"]
'hello'.partition('')       # => ["", "", "hello"]
'тест'.partition('т')       # => ["", "т", "ест"]
'こんにちは'.partition('に')  # => ["こん", "に", "ちは"]

If the pattern is not matched, returns a copy of self and two empty strings:

'hello'.partition('x') # => ["hello", "", ""]

String#rpartition

Returns a 3-element array of substrings of self.

Matches a pattern against self, scanning backwards from the end. The pattern is:

string_or_regexp itself, if it is a Regexp.
Regexp.quote(string_or_regexp), if string_or_regexp is a string.

If the pattern is matched, returns pre-match, last-match, post-match:

'hello'.rpartition('l')      # => ["hel", "l", "o"]
'hello'.rpartition('ll')     # => ["he", "ll", "o"]
'hello'.rpartition('h')      # => ["", "h", "ello"]
'hello'.rpartition('o')      # => ["hell", "o", ""]
'hello'.rpartition(/l+/)     # => ["hel", "l", "o"]
'hello'.rpartition('')       # => ["hello", "", ""]
'тест'.rpartition('т')       # => ["тес", "т", ""]
'こんにちは'.rpartition('に')  # => ["こん", "に", "ちは"]

If the pattern is not matched, returns two empty strings and a copy of self:

'hello'.rpartition('x') # => ["", "", "hello"]

Float#arg

Returns 0 if the value is positive, pi otherwise.

Float#numerator

Returns the numerator. The result is machine dependent.

n = 0.3.numerator    #=> 5404319552844595
d = 0.3.denominator  #=> 18014398509481984
n.fdiv(d)            #=> 0.3

Float#rationalize

Returns a simpler approximation of the value (flt-|eps| <= result <= flt+|eps|). If the optional argument eps is not given, it will be chosen automatically.

0.3.rationalize          #=> (3/10)
1.333.rationalize        #=> (1333/1000)
1.333.rationalize(0.01)  #=> (4/3)

Fiber::current

Returns the current fiber. If you are not running in the context of a fiber this method will return the root fiber.

Fiber#storage

Returns a copy of the storage hash for the fiber. The method can only be called on the Fiber.current.

Fiber#storage=

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

Raises an exception in the fiber at the point at which the last Fiber.yield was called. If the fiber has not been started or has already run to completion, raises FiberError. If the fiber is yielding, it is resumed. If it is transferring, it is transferred into. But if it is resuming, raises FiberError.

With no arguments, raises a RuntimeError. With a single String argument, raises a RuntimeError with the string as a message. Otherwise, the first parameter should be the name of an Exception class (or an object that returns an Exception object when sent an exception message). The optional second parameter sets the message associated with the exception, and the third parameter is an array of callback information. Exceptions are caught by the rescue clause of begin...end blocks.

Fiber#backtrace

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

Fiber#transfer

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

File::chardev?

Returns true if filepath points to a character device, false otherwise.

File.chardev?($stdin)     # => true
File.chardev?('t.txt')     # => false

Object#display

Writes self on the given port:

1.display
"cat".display
[ 4, 5, 6 ].display
puts

Output:

1cat[4, 5, 6]

Exception#backtrace

Returns any backtrace associated with the exception. The backtrace is an array of strings, each containing either “filename:lineNo: in ‘method”’ or “filename:lineNo.”

def a
  raise "boom"
end

def b
  a()
end

begin
  b()
rescue => detail
  print detail.backtrace.join("\n")
end

produces:

prog.rb:2:in `a'
prog.rb:6:in `b'
prog.rb:10

In the case no backtrace has been set, nil is returned

ex = StandardError.new
ex.backtrace
#=> nil

NoMethodError#args

Return the arguments passed in as the third parameter to the constructor.