Calls the block with each repeated combination of length n of the elements of self; each combination is an Array; returns self. The order of the combinations is indeterminate.

When a block and a positive Integer argument n are given, calls the block with each n-tuple repeated combination of the elements of self. The number of combinations is (n+1)(n+2)/2.

n = 1:

a = [0, 1, 2]
a.repeated_combination(1) {|combination| p combination }

Output:

[0]
[1]
[2]

n = 2:

a.repeated_combination(2) {|combination| p combination }

Output:

[0, 0]
[0, 1]
[0, 2]
[1, 1]
[1, 2]
[2, 2]

If n is zero, calls the block once with an empty Array.

If n is negative, does not call the block:

a.repeated_combination(-1) {|combination| fail 'Cannot happen' }

Returns a new Enumerator if no block given:

a = [0, 1, 2]
a.repeated_combination(2) # => #<Enumerator: [0, 1, 2]:combination(2)>

Using Enumerators, it’s convenient to show the combinations and counts for some values of n:

e = a.repeated_combination(0)
e.size # => 1
e.to_a # => [[]]
e = a.repeated_combination(1)
e.size # => 3
e.to_a # => [[0], [1], [2]]
e = a.repeated_combination(2)
e.size # => 6
e.to_a # => [[0, 0], [0, 1], [0, 2], [1, 1], [1, 2], [2, 2]]

Like backtrace, but returns each line of the execution stack as a Thread::Backtrace::Location. Accepts the same arguments as backtrace.

f = Fiber.new { Fiber.yield }
f.resume
loc = f.backtrace_locations.first
loc.label  #=> "yield"
loc.path   #=> "test.rb"
loc.lineno #=> 1

Returns any backtrace associated with the exception. This method is similar to Exception#backtrace, but the backtrace is an array of Thread::Backtrace::Location.

This method is not affected by Exception#set_backtrace().

Creates module functions for the named methods. These functions may be called with the module as a receiver, and also become available as instance methods to classes that mix in the module. Module functions are copies of the original, and so may be changed independently. The instance-method versions are made private. If used with no arguments, subsequently defined methods become module functions. String arguments are converted to symbols. 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 one
    "This is one"
  end
  module_function :one
end
class Cls
  include Mod
  def call_one
    one
  end
end
Mod.one     #=> "This is one"
c = Cls.new
c.call_one  #=> "This is one"
module Mod
  def one
    "This is the new one"
  end
end
Mod.one     #=> "This is one"
c.call_one  #=> "This is the new one"

Returns the fractional part of the day.

DateTime.new(2001,2,3,12).day_fraction    #=> (1/2)

Returns true if the set is a proper subset of the given set.

The block need not return a String object:

csv = CSV.open(path, headers: true)
csv.header_convert {|header, field_info| header.to_sym }
table = csv.read
table.headers # => [:Name, :Value]

If converter_name is given, the block is not called:

csv = CSV.open(path, headers: true)
csv.header_convert(:downcase) {|header, field_info| fail 'Cannot happen' }
table = csv.read
table.headers # => ["name", "value"]

Raises a parse-time exception if converter_name is not the name of a built-in field converter:

csv = CSV.open(path, headers: true)
csv.header_convert(:nosuch)
# Raises NoMethodError (undefined method `arity' for nil:NilClass)
csv.read

Returns the Ruby source filename and line number of the binding object.

Raises PStore::Error if the calling code is not in a PStore#transaction.

Returns the Ruby source filename and line number containing this proc or nil if this proc was not defined in Ruby (i.e. native).

Returns the Ruby source filename and line number containing this method or nil if this method was not defined in Ruby (i.e. native).

Returns the Ruby source filename and line number containing this method or nil if this method was not defined in Ruby (i.e. native).

Returns the execution stack for the target thread—an array containing backtrace location objects.

See Thread::Backtrace::Location for more information.

This method behaves similarly to Kernel#caller_locations except it applies to a specific thread.

With a block given, calls the block with each element, but in reverse order; returns self:

a = []
(1..4).reverse_each {|element| a.push(-element) } # => 1..4
a # => [-4, -3, -2, -1]

a = []
%w[a b c d].reverse_each {|element| a.push(element) }
# => ["a", "b", "c", "d"]
a # => ["d", "c", "b", "a"]

a = []
h.reverse_each {|element| a.push(element) }
# => {:foo=>0, :bar=>1, :baz=>2}
a # => [[:baz, 2], [:bar, 1], [:foo, 0]]

With no block given, returns an Enumerator.

Returns the source file origin from the given object.

See ::trace_object_allocations for more information and examples.

Returns the original line from source for from the given object.

See ::trace_object_allocations for more information and examples.

Constant time memory comparison. Inputs are hashed using SHA-256 to mask the length of the secret. Returns true if the strings are identical, false otherwise.

Specifies a Proc object proc to determine completion behavior. It should take input string and return an array of completion candidates.

The default completion is used if proc is nil.

The String that is passed to the Proc depends on the Readline.completer_word_break_characters property. By default the word under the cursor is passed to the Proc. For example, if the input is “foo bar” then only “bar” would be passed to the completion Proc.

Upon successful completion the Readline.completion_append_character will be appended to the input so the user can start working on their next argument.

Examples

Completion for a Static List

require 'readline'

LIST = [
  'search', 'download', 'open',
  'help', 'history', 'quit',
  'url', 'next', 'clear',
  'prev', 'past'
].sort

comp = proc { |s| LIST.grep(/^#{Regexp.escape(s)}/) }

Readline.completion_append_character = " "
Readline.completion_proc = comp

while line = Readline.readline('> ', true)
  p line
end

Completion For Directory Contents

require 'readline'

Readline.completion_append_character = " "
Readline.completion_proc = Proc.new do |str|
  Dir[str+'*'].grep(/^#{Regexp.escape(str)}/)
end

while line = Readline.readline('> ', true)
  p line
end

Autocomplete strategies

When working with auto-complete there are some strategies that work well. To get some ideas you can take a look at the completion.rb file for irb.

The common strategy is to take a list of possible completions and filter it down to those completions that start with the user input. In the above examples Enumerator.grep is used. The input is escaped to prevent Regexp special characters from interfering with the matching.

It may also be helpful to use the Abbrev library to generate completions.

Raises ArgumentError if proc does not respond to the call method.

Returns the completion Proc object.

Returns the number of malloc() allocations.

Only available if ruby was built with CALC_EXACT_MALLOC_SIZE.

Start a dRuby server locally.

The new dRuby server will become the primary server, even if another server is currently the primary server.

uri is the URI for the server to bind to. If nil, the server will bind to random port on the default local host name and use the default dRuby protocol.

front is the server’s front object. This may be nil.

config is the configuration for the new server. This may be nil.

See DRbServer::new.

Start a dRuby server locally.

The new dRuby server will become the primary server, even if another server is currently the primary server.

uri is the URI for the server to bind to. If nil, the server will bind to random port on the default local host name and use the default dRuby protocol.

front is the server’s front object. This may be nil.

config is the configuration for the new server. This may be nil.

See DRbServer::new.

Get the ‘current’ server.

In the context of execution taking place within the main thread of a dRuby server (typically, as a result of a remote call on the server or one of its objects), the current server is that server. Otherwise, the current server is the primary server.

If the above rule fails to find a server, a DRbServerNotFound error is raised.

Get the ‘current’ server.

In the context of execution taking place within the main thread of a dRuby server (typically, as a result of a remote call on the server or one of its objects), the current server is that server. Otherwise, the current server is the primary server.

If the above rule fails to find a server, a DRbServerNotFound error is raised.

Stop the local dRuby server.

This operates on the primary server. If there is no primary server currently running, it is a noop.