ruby singleton

The first type (lazy, thread insecure):public class Singleton { private static Singleton instance; private Singleton (){} public static Singleton getInstance() { if (instance == null) { instance = new Singleton(); } return instance; } } The second type (laz

The first type (lazy, thread insecure):Java code public class Singleton { private static Singleton instance; Private Singleton () {} public static Singleton getinstance () { if (instance = = null) { Instance = new Singleton (); } ret

Share the code for implementing the singleton mode in objective-C. It seems that the design pattern is rarely mentioned in MAC development... At least we haven't seen any design patterns implemented with objective-c... Code Code highlighting produced by Actipro CodeHighlighter (freeware)http://www.CodeHighlighter.com/--> StaticDatamanager*Shareddatamanager=Nil; +(Datamanager*) Sharedmanager{@ Synchronized (Self){If(Shareddatamanager=

Recently I am working on a winform application.ProgramWhen the MDI form is used, a lot of trouble is encountered. One of them is how to solve the problem of not letting the child form be instantiated multiple times. I have searched the internet for a long time and found many solutions. Here I will introduce some simple methods. In fact, this is the singleton mode in the classic 23 design patterns. The following uses C # To implement it: Suppose

1. DefinitionSingleton mode (Singleton), also known as the list mode, is a common software design pattern. When you apply this pattern, the class of the Singleton object must guarantee that only one instance exists. Many times the entire system needs to have only one global object, which helps us coordinate the overall behavior of the system. For example, in a server program, the configuration information f

Matrix concatenation algorithm implemented by Ruby and ruby matrix concatenation Dynamic Planning solves the problem of matrix concatenation, generates matrix sequences randomly, and outputs results in the form of (A1 (A2A3) (A4A5. Code: #encoding: utf-8=beginauthor: xu jin, 4100213date: Oct 28, 2012MatrixChainto find an optimum order by using MatrixChain algorithmexample output:The given array is:[30, 35,

Simple implementation of the Bubble Sorting Algorithm and Ruby version, and the Bubble Sorting Algorithm ruby Algorithm principle: Compares adjacent elements. If the first is bigger than the second, exchange the two of them.Perform the same operation on each adjacent element, from the first to the last. At this point, the final element should be the largest number.Repeat the preceding steps for all elements

machineInitialization completeStart the environment execution vagrant Halt shutdown environment by executing vagrant up in the appropriate directory when usedOther points of attentionAfter successful initialization, a configuration file named Vagrantfile is generated in the appropriate directory, which can be set for network, memory size, and other content.This article is from the "7692323" blog, please be sure to keep this source http://7702323.blog.51cto.com/7692323/1596334Build a

A few Ruby tips and Ruby tips Sequential call of code blocksCopy codeThe Code is as follows:Def touch_downYield [3, 7]Puts "touchdown! "EndTouch_down do | (first_down, second_down) |Puts "# {first_down} yards on the run"Puts "# {second_down} yards passed"End=> "3 yards on the run"=> "7 yards passed"=> "Touchdown! " It mainly refers to the use of array in block Retrieve elements from arrayCopy codeThe Code i

Example of the use of hundreds of semicolons and literal values in Ruby: ruby percent Use % () (abbreviated as % Q) for a single line string that requires interpolation and embedding double quotation marks ). Multi-line string, preferably heredocs. # bad (no interpolation needed) %( Do not use % q for strings without 'and. Unless many characters need to be escaped, the normal string is more readable.

A summary of some common file operations in Ruby and a summary of ruby operations A lot of Ruby beginners need to learn. Now we are trying to use Ruby to write a script. Many file-related operations are used, which are sorted in stages here. This facilitates subsequent searches. Whether the file or directory exists

Collections writing guide in Ruby and Ruby collections writing guide Preference array and the literal representation of Hash (unless you need to pass parameters to their constructor ). # bad arr = Array.new hash = Hash.new # good arr = [] hash = {} When you need an array with elements of words (no spaces or special characters), you always use % w to define a string array. Apply this rule to only two

Installation will not say, the official website has, but today released ruby2.3, so updateEnter the. Rbenv directory, perform a git pull update, but update rbenv, execute rbenv install-l and do not have the latest 2.3.0 release version.Then I looked at the git repository for the Ruby-build plugin, with 2.3 code. Suspect this also to be updated, so.Go to the. Rbenv/plugins/ruby-build directory and execute gi

Ruby parsing JSONRuby Parsing JSON Example: JSON = ' ["A", "B", "C"] ' puts "Unsafe #{unsafe_json (JSON). Inspect}" #输出Unsafe ["A", "B", "C"] Ruby parses JSON to parse the above JSON string into array. Such a method is not safe, for example: JSON = ' puts ' Danger'll Robinson ' puts ' Unsafe #{unsafe_json (JSON). Inspect} " And what should we export? Unfortunately, there is

;> 1.instance_variable_get (: @my_var) => "World" Behavioral behavior is the action on the object, is the way we often say. The invocation of a Ruby method, similar to Smalltalk or OBJECTIV-C, takes message mode. Calling a method is equivalent to sending a message to this object. So a call to a method can do the same: In Ruby, the state, which is the instance variable, is stored in the object, a

Ruby's philosophy is based on a basic element that makes programmers happy. Ruby is very focused on the happiness of programmers and offers a number of different ways to implement it. Its metaprogramming capabilities enable programmers to write code that is generated dynamically at run time. Its threading capabilities allow programmers to have an elegant way of writing multithreaded code. Its hook method allows programmers to extend the behavior of a

Detailed descriptions of hook methods in Ruby This article mainly introduces the detailed explanation of the hook method in Ruby. This article explains what is the hook method, extended, extended, prepended, inherited, and so on in included, Devise, for more information, see Ruby's philosophy is based on a basic element, that is, to make programmers happy. Ruby p

The number of instances of a class can only be instantiated once.For example: Xiao Wang and Xiao Li through the doorbell to communicate, first of all to judge the small Wang home whether there is a door, if there is no door, if there is a door directly back to the door.var Xiaowang = (function (argument) {var men;var Xiaowangjia = function (message) {this.menling = message;}var info = {Sendmsg:function (message) {if (!men) {Men = new Xiaowangjia (message);}return men;}}//Public properties and me

Common Ruby file operation code instances and ruby code instances # Create a 222. rb file and the input character File = file. open ("222.rb"," w + ") file. puts "123 \ nwadwa \ n12124124 \ ndwdw" file. close # output 222. rb content File. open ("222.rb"," r + ") do | file | while line = file. getsputs lineendend # directly use IO to operate the file IO. foreach ("222.rb") do | line | puts line if line = ~

Ruby-implemented file self-deletion code sharing, ruby-implemented code sharing Because the File Deletion mechanism in windows is different from that in unix like, so does not guarantee that the following code can be used in windows. Which of the following kids shoes can help me test it in windows! Copy codeThe Code is as follows:#! /Usr/bin/ruby 5. times do |