Finds and returns the object in nested objects that is specified by name and identifiers. The nested objects may be instances of various classes. See Dig Methods.
Examples:
require "ostruct" address = OpenStruct.new("city" => "Anytown NC", "zip" => 12345) person = OpenStruct.new("name" => "John Smith", "address" => address) person.dig(:address, "zip") # => 12345 person.dig(:business_address, "zip") # => nil
With no argument, returns the first element of self, if it exists:
(1..4).first # => 1 ('a'..'d').first # => "a"
With non-negative integer argument n given, returns the first n elements in an array:
(1..10).first(3) # => [1, 2, 3] (1..10).first(0) # => [] (1..4).first(50) # => [1, 2, 3, 4]
Raises an exception if there is no first element:
(..4).first # Raises RangeError
Performs division and returns the value as a Float.
Rational(2, 3).fdiv(1) #=> 0.6666666666666666 Rational(2, 3).fdiv(0.5) #=> 1.3333333333333333 Rational(2).fdiv(3) #=> 0.6666666666666666
Returns the Encoding object that represents the encoding of obj.
Returns true if the set and the given enumerable have no element in common. This method is the opposite of intersect?.
Set[1, 2, 3].disjoint? Set[3, 4] #=> false Set[1, 2, 3].disjoint? Set[4, 5] #=> true Set[1, 2, 3].disjoint? [3, 4] #=> false Set[1, 2, 3].disjoint? 4..5 #=> true
Divides the set into a set of subsets according to the commonality defined by the given block.
If the arity of the block is 2, elements o1 and o2 are in common if block.call(o1, o2) is true. Otherwise, elements o1 and o2 are in common if block.call(o1) == block.call(o2).
require 'set' numbers = Set[1, 3, 4, 6, 9, 10, 11] set = numbers.divide { |i,j| (i - j).abs == 1 } set #=> #<Set: {#<Set: {1}>, # #<Set: {11, 9, 10}>, # #<Set: {3, 4}>, # #<Set: {6}>}>
Returns an enumerator if no block is given.
Finds and returns an object among nested objects. The nested objects may be instances of various classes. See Dig Methods.
Given symbol or string argument name, returns the object that is specified by name and identifiers:
Foo = Struct.new(:a) f = Foo.new(Foo.new({b: [1, 2, 3]})) f.dig(:a) # => #<struct Foo a={:b=>[1, 2, 3]}> f.dig(:a, :a) # => {:b=>[1, 2, 3]} f.dig(:a, :a, :b) # => [1, 2, 3] f.dig(:a, :a, :b, 0) # => 1 f.dig(:b, 0) # => nil
Given integer argument n, returns the object that is specified by n and identifiers:
f.dig(0) # => #<struct Foo a={:b=>[1, 2, 3]}> f.dig(0, 0) # => {:b=>[1, 2, 3]} f.dig(0, 0, :b) # => [1, 2, 3] f.dig(0, 0, :b, 0) # => 1 f.dig(:b, 0) # => nil
Equivalent to self.to_s.encoding; see String#encoding.
Returns the birth time for the file. If the platform doesn’t have birthtime, raises NotImplementedError.
See File.birthtime.
Creates a pair of sockets connected each other.
domain should be a communications domain such as: :INET, :INET6, :UNIX, etc.
socktype should be a socket type such as: :STREAM, :DGRAM, :RAW, etc.
protocol should be a protocol defined in the domain, defaults to 0 for the domain.
s1, s2 = Socket.pair(:UNIX, :STREAM, 0) s1.send "a", 0 s1.send "b", 0 s1.close p s2.recv(10) #=> "ab" p s2.recv(10) #=> "" p s2.recv(10) #=> "" s1, s2 = Socket.pair(:UNIX, :DGRAM, 0) s1.send "a", 0 s1.send "b", 0 p s2.recv(10) #=> "a" p s2.recv(10) #=> "b"
Creates a pair of sockets connected each other.
domain should be a communications domain such as: :INET, :INET6, :UNIX, etc.
socktype should be a socket type such as: :STREAM, :DGRAM, :RAW, etc.
protocol should be a protocol defined in the domain, defaults to 0 for the domain.
s1, s2 = Socket.pair(:UNIX, :STREAM, 0) s1.send "a", 0 s1.send "b", 0 s1.close p s2.recv(10) #=> "ab" p s2.recv(10) #=> "" p s2.recv(10) #=> "" s1, s2 = Socket.pair(:UNIX, :DGRAM, 0) s1.send "a", 0 s1.send "b", 0 p s2.recv(10) #=> "a" p s2.recv(10) #=> "b"
Creates a pair of sockets connected to each other.
type should be a socket type such as: :STREAM, :DGRAM, :RAW, etc.
protocol should be a protocol defined in the domain. 0 is default protocol for the domain.
s1, s2 = UNIXSocket.pair s1.send "a", 0 s1.send "b", 0 p s2.recv(10) #=> "ab"
Creates a pair of sockets connected to each other.
type should be a socket type such as: :STREAM, :DGRAM, :RAW, etc.
protocol should be a protocol defined in the domain. 0 is default protocol for the domain.
s1, s2 = UNIXSocket.pair s1.send "a", 0 s1.send "b", 0 p s2.recv(10) #=> "ab"
Finds and returns the object in nested objects that is specified by key and identifiers. The nested objects may be instances of various classes. See Dig Methods.
Nested Hashes:
h = {foo: {bar: {baz: 2}}} h.dig(:foo) # => {:bar=>{:baz=>2}} h.dig(:foo, :bar) # => {:baz=>2} h.dig(:foo, :bar, :baz) # => 2 h.dig(:foo, :bar, :BAZ) # => nil
Nested Hashes and Arrays:
h = {foo: {bar: [:a, :b, :c]}} h.dig(:foo, :bar, 2) # => :c
This method will use the default values for keys that are not present:
h = {foo: {bar: [:a, :b, :c]}} h.dig(:hello) # => nil h.default_proc = -> (hash, _key) { hash } h.dig(:hello, :world) # => h h.dig(:hello, :world, :foo, :bar, 2) # => :c
Opens an IRB session where binding.irb is called which allows for interactive debugging. You can call any methods or variables available in the current scope, and mutate state if you need to.
Given a Ruby file called potato.rb containing the following code:
class Potato def initialize @cooked = false binding.irb puts "Cooked potato: #{@cooked}" end end Potato.new
Running ruby potato.rb will open an IRB session where binding.irb is called, and you will see the following:
$ ruby potato.rb
From: potato.rb @ line 4 :
1: class Potato
2: def initialize
3: @cooked = false
=> 4: binding.irb
5: puts "Cooked potato: #{@cooked}"
6: end
7: end
8:
9: Potato.new
irb(#<Potato:0x00007feea1916670>):001:0>
You can type any valid Ruby code and it will be evaluated in the current context. This allows you to debug without having to run your code repeatedly:
irb(#<Potato:0x00007feea1916670>):001:0> @cooked => false irb(#<Potato:0x00007feea1916670>):002:0> self.class => Potato irb(#<Potato:0x00007feea1916670>):003:0> caller.first => ".../2.5.1/lib/ruby/2.5.0/irb/workspace.rb:85:in `eval'" irb(#<Potato:0x00007feea1916670>):004:0> @cooked = true => true
You can exit the IRB session with the exit command. Note that exiting will resume execution where binding.irb had paused it, as you can see from the output printed to standard output in this example:
irb(#<Potato:0x00007feea1916670>):005:0> exit Cooked potato: true
See IRB for more information.
Return candidates for word.
Parses environment variable env or its uppercase with splitting like a shell.
env defaults to the basename of the program.
Returns the binding associated with prc.
def fred(param) proc {} end b = fred(99) eval("param", b.binding) #=> 99
Deactivates the trace
Return true if trace was enabled. Return false if trace was disabled.
trace.enabled? #=> true trace.disable #=> true (previous status) trace.enabled? #=> false trace.disable #=> false
If a block is given, the trace will only be disable within the scope of the block.
trace.enabled? #=> true trace.disable do trace.enabled? # only disabled for this block end trace.enabled? #=> true
Note: You cannot access event hooks within the block.
trace.disable { p tp.lineno } #=> RuntimeError: access from outside
Return the generated binding object from event.
Note that for :c_call and :c_return events, the method will return nil, since C methods themselves do not have bindings.
When RubyGems is required, Kernel#require is replaced with our own which is capable of loading gems on demand.
When you call require 'x', this is what happens:
If the file can be loaded from the existing Ruby loadpath, it is.
Otherwise, installed gems are searched for a file that matches. If it’s found in gem ‘y’, that gem is activated (added to the loadpath).
The normal require functionality of returning false if that file has already been loaded is preserved.
Returns a Binding object, describing the variable and method bindings at the point of call. This object can be used when calling Binding#eval to execute the evaluated command in this environment, or extracting its local variables.
class User def initialize(name, position) @name = name @position = position end def get_binding binding end end user = User.new('Joan', 'manager') template = '{name: @name, position: @position}' # evaluate template in context of the object eval(template, user.get_binding) #=> {:name=>"Joan", :position=>"manager"}
Binding#local_variable_get can be used to access the variables whose names are reserved Ruby keywords:
# This is valid parameter declaration, but `if` parameter can't # be accessed by name, because it is a reserved word. def validate(field, validation, if: nil) condition = binding.local_variable_get('if') return unless condition # ...Some implementation ... end validate(:name, :empty?, if: false) # skips validation validate(:name, :empty?, if: true) # performs validation
Returns the first element or elements.
With no argument, returns the first element, or nil if there is none:
(1..4).first # => 1 %w[a b c].first # => "a" {foo: 1, bar: 1, baz: 2}.first # => [:foo, 1] [].first # => nil
With integer argument n, returns an array containing the first n elements that exist:
(1..4).first(2) # => [1, 2] %w[a b c d].first(3) # => ["a", "b", "c"] %w[a b c d].first(50) # => ["a", "b", "c", "d"] {foo: 1, bar: 1, baz: 2}.first(2) # => [[:foo, 1], [:bar, 1]] [].first(2) # => []
Returns a Digest subclass by name
require 'openssl' OpenSSL::Digest("MD5") # => OpenSSL::Digest::MD5 Digest("Foo") # => NameError: wrong constant name Foo