ruby singleton

1. Auxiliary methods2. StringEnter "IRB" into the ruby command-line development environment, and the controller starts by executing "rails console" on the command line.(1) String connection>>"foo"+"bar"="foobar" (2) Interpolation by special syntax #{}>>first_name="Amy" ="Amy">>" #{first_name} Sun"+"Amy Sun "(3) The difference between a single-quote string and a double-quote string: Single-quote strings they really are literal values, contain only the

When I started my ruby journey, I wrote my study notes for people with other OO language experiences. Let's take a look at the magic ruby. The first sample! First meeting. # ! /Usr/bin/ENV Ruby Class MegagreeterAttr_accessor: names # Create the object Def Initialize (names = " World " )@ Names = NamesEnd # Say hi

entities are destroyed Delete_all: All associated entities are deleted directly from the database, unrecoverable nullify: foreign keys are Set to NULL, unrecoverable restrict_with_exception: Throw exception hint Restrict_with_error: Throw error prompt 5, Foreign_key: Define column name for foreign Key 6, inverse_of : Indicates the inverse associated entity 7, Primary_key: Indicates the associated item ID 8, through: Indicates that a many-to-many relationship uses a third-party entity 9, validat

1.1 Singleton (Single Instance) If we think that a class only needs to generate one instance, we will design it as Singleton (single instance mode ). Singleton is the most frequently used mode in our projects,This mode ensures that a class has only one instance and provides a global access point to it.. Singleton is a

Explain the code block object Proc in Ruby, and explain the ruby object proc. Proc object Proc is a block conversion object. There are four methods to create a Proc: Sample Code # Method 1 inc = Proc. new {| x + 1} inc. call (2) #=> 3 # method 2 inc = lambda {| x + 1} inc. call (2) #=> 3 # method 3 inc =-> (x) {x + 1} inc. call (2) #=> 3 # Method 4 inc = proc {| x + 1} inc. call (2) # => 3 In addition to th

Various sorting algorithms implemented by Ruby and Ruby Time Complexity: Average (n ^ 2) Bubble sortCopy codeThe Code is as follows:Def bubble_sort ()(A. size-2). downto (0) do | I |(0.. I). each do | j |A [j], a [j + 1] = a [j + 1], a [j] if a [j]> a [j + 1]EndEndReturnEnd Selection sortCopy codeThe Code is as follows:Def selection_sort ()B = []A. size. times do | I |Min = a. minB A. delete_at (a. index (m

Class methods and class extensions in Ruby object-oriented programming, ruby Object-Oriented Programming Class Method The essence of a class method is a single-piece method that lives in a single-piece class of this class. Three methods are defined: # Method 1 def MyClass. a_class_method; end # method 2 class MyClass def self. anther_class_method; endend # method 3 * class MyClass class The third method in

Ruby-based optimal binary search tree algorithm and ruby-based optimal binary search algorithm The pseudo code in the introduction to algorithms is rewritten, plus the constructor for the solution of the first question in the Introduction Class Exercises.Copy codeThe Code is as follows:# Encoding: UTF-8= BeginAuthor: xu jinDate: Nov 11,201 2Optimal Binary Search TreeTo find by using EditDistance algorithmRe

Comparison of class variables and instance variables in Ruby, ruby class variable instances 1. The class variable name starts with @. A Class variable is shared by all instance objects of the class. The instance variable name starts with @, and each instance object has its own different instance variables; 2. class variables must be initialized before use; otherwise, an error is reported during use. If the

Summary of loop statements in ruby and summary of ruby loop statements While (when ...) Loop 　 　 While Condition Statement 1; Statement 2; statement... End Single Row while LOOP (Statement 1; Statement 2; statement... ) While Condition Until (...) Loop Until condition = while not (condition) For... In Loop 　 　 For variable in obj

A singleton pattern in C + +The singleton mode, also known as the single-piece mode, the list mode, is probably the most widely used design pattern. The intent is to ensure that a class has only one instance and provides a global access point to access it, which is shared by all program modules. There are many places need such a function module, such as the log output of the system, the GUI application must

A singleton object (Singleton) is a common design pattern. In Java applications, singleton objects guarantee that only one instance of the object exists in a JVM. There are several benefits to this model:1, some classes are created more frequently, for some large objects, this is a lot of overhead.2, eliminate the new operator, reduce the use of system memory fre

Objectivehas introduced and learned two creation patterns, today to learn about another very common creation mode, the singleton mode.The singleton mode is also known as a single-piece mode (or monomer mode), and the primary function is to control the number of instances of a type as one, and only one.The realization of singleton mode in single case modeThere are

A concept Introduction:The so-called singleton mode, simply put, is to ensure that only one instance of a class exists throughout the application, and that it instantiates itself and provides this instance to the system as a whole. A singleton object is usually used as a carrier for storing configuration information in a program, because it guarantees that other objects will read consistent information. For

String processing in ruby is flexible. "ABC" [0] returns 97 as"ABC" [1] 98"ABC" [2] 99"ABC" [3] Nil"ABC" [-1] 99 forward number"ABC" [-2] 98"ABC" [-3] 97"ABC" [-4] Nil "ABC" * 2 returns "abcabc" supporting Multiplication "ABC" + "def" returns "abcdef" "Abcdef" [] "A" extracts one digit from the position 0"Abcdef" [1, 3] "BCD""Abcdef" [-3, 3] "def""Abcdef" [1 .. 3] "BC" from 1 to 3 Come to a riddleProgram Code highlighting produced by Acti

Arrays in ruby are created by square brackets. The initial values can be placed in square brackets and separated by commas. array elements can be of different types and support addition and multiplication. Ary = [1, 2, "3"]Ary * 2 Returns [1, 2, "3", 1, 2, "3"]Ary + ["Lee", "ho"] returns [1, 2, "3", "Lee", "ho"]Ary [] returns [1, 2] and obtains two elements starting from position 0.Ary [0 .. 2] returns [1, 2, "3"] From position 0 to position 2 Arr

I used to want to use Java for something similar. Today I see Ruby already has ----- Gem install Chardet-y ----- Require 'rubygems'Require 'universaldetector'Require 'net/http'Net: http. version_1_2Net: http. Start ('www .sina.com.cn ') {| HTTP |Data = http. Get ("/"). BodyP universaldetector: chardet (data)}It is a Python version transplant, and there is a confidence parameter. I tested several sites in China and it is very accurate. However,

inheritance of loading modules and classes: Module MdefPuts "' The ' method ' in module M"EndEnd Class CInclude MEnd Class D End obj = d.newObj.reportThe example method is defined in module M, the C class is mixed with module M, Class D is a subclass of Class C, and obj is an instance of Class D, the object of obj can call the method. From an object's perspective, suppose you are an object, someone sends you a message, you have to find a way to respond, and the idea is probably like this:

The singleton mode, also known as the single-piece mode, the list mode, is probably the most widely used design pattern. The intent is to ensure that a class has only one instance, and provides a global access point to it, which is shared by all program modules. There are a lot of places need this function module, such as the log output of the system, GUI application must be single mouse, modem connection need one and only need a telephone line, the o

First, what is a singleton modeEnsure that a class has only one instance and provides a global access point to access itSecond, the advantages Controlled access to a unique instance Simple interest is equivalent to a global variable, but prevents the namespace from being contaminated Concepts similar to simple interest mode: Global variables, static variables (methods)How can Why use singleton