ruby etl

Four Methods for Equality judgment in Ruby and four methods for ruby equality judgment It has long been known that ruby has four equality judgment methods: "=", "=", and "equal ?" And "eql ?", It is used in common programs, but I feel that I lack a deep understanding of it. When I read some of the rails source code today, I cannot determine the meaning of one of

We strongly recommend that you use the following Online Learning Websites: http://tryruby.org: Ruby returns the last value in the method by default. To return multiple values, you can use an array. You can return a value by forcibly declaring return. The basic output method is to use puts (output line) and print (print directly ). The Basic Input Method is gets (read a row that contains '\ n' at the end of the row, which can be eliminated by cho

Basic Learning notes for Ruby metaprogramming and ruby learning notes Note 1:The Code contains variables, classes, and methods, collectively referred to as language construct ). # test.rbclass Greeting def initialize(text) @text = text end def welcome @text endendmy_obj = Greeting.new("hello")puts my_obj.classputs my_obj.class.instance_methods(false) #false means not inheritedputs my_obj.instance_variable

Assignment related operations in Ruby programming and ruby programming assignment In earlier versions of Ruby, the return value of the value assignment statement is the return value of the method that sets this attribute. In Ruby1.8, the value of the value assignment statement is always the value of the parameter, and the return value of the method is lost. class

Ruby learning plan-(0) preface, ruby Preface Preface Currently, C, C ++, Java, Object-C, and Swift programming languages have been used. The most familiar language is oc. After all, it depends on him for dinner. It is only a beginner's path for other languages. Because he has been engaged in iPhone app development, recently, I wanted to develop a project by myself, but there was no backend, so I was so

Global variable $ XX Object variable @ xx Local variable [A-Z] xx Constant [A-Z] xx Two pseudo variables self and nil:Self is actually a global variable pointing to the current object. The value of this variable is controlled by the interpreter and can only be read and cannot be modified.Nil is also a global variable controlled by the interpreter and cannot be assigned a value. 1. Global variable $ XXGlobal variables should be used with caution because their scope is script-level and can

Ruby is a powerful object-oriented scripting language that allows you to quickly and easily object-oriented programming. Sometimes it's a little "fuss" to develop small projects using formal object-oriented languages such as Smalltalk, Eiffel, or C + +. And Ruby just meets the needs of these object-oriented programming. Of course, you can also use Ruby for genera

Tutorial on creating and using hash in Ruby and ruby hash Hash is a set of key-value pairs similar to "employee" => "salary. Hash indexes are completed by any key of any object type, rather than an integer index. Others are similar to arrays. The hash traversal order by key or value seems random, and is generally not in the insertion order. If you try to access the hash using a key that does not exist, the

An example is provided to explain the regular expressions in Ruby and the regular expressions in ruby. A regular expression is a special character sequence that can help match or find other strings or strings. The pattern used maintains a special syntax. The regular expression text is a slash between a pattern or any separator % r is as follows:Syntax: Copy codeThe Code is as follows:/pattern//Pattern/im #

Ruby meta-programming summary, ruby Summary When I was asked such questions today, I used to think that this is a broad concept. Even if I have used these features, but I still don't know this is called "metaprogramming" until today when I was asked, I just had an epiphany, and then I made a small summary on the Internet with some of my actual metaprogramming. The so-called meta-programming in

For Ruby introduction, see: http://www.ruby-lang.org/zh_CN/about/ I. IRB Interactive Ruby help and consoleProgramIn Windows. You can directly execute Ruby in IRB.Code. For example: Code highlighting produced by Actipro CodeHighlighter (freeware)http://www.CodeHighlighter.com/--> IRB (main ): 001 : 0 > " Hello World " => " Hello W

Enter the command line in ruby to compile sass (ruby) and rubysass Ruby(Or cmd) Enter the command line to compile sass as follows: (1) For example: first, create a total folder under drive F, such as the test folder, and then create folders such as html, images, js, and sass under the folder. (2) Create the sass file to be used in the sass folder. For example, co

I have always been very interested in Ruby on Rails. I want to see something that has been praised by many people, but I have been working on windows development, it is still a headache to build the development environment of Ruby on Rails, Which is why Ruby on rails has not been studied. I just saw InstantRails In javaeye, an All-In-One suite, which can help you

Example of writing code for exception handling in Ruby, and ruby Exception Handling A single exception uses the fail keyword only when an exception is caught and thrown repeatedly (because you do not fail here, but are accurate and intentionally throw an exception ). begin fail 'Oops' rescue => error raise if error.message != 'Oops' end Do not specify an accurate RuntimeError for fail/raise. # bad

Tutorial on interrupt and return in Ruby programming and tutorial on ruby programming usage The use of the return, break, and next keywords involves the issue of jumping out of the scope. Their difference lies in the different scopes of different keywords jumping out, because there are code blocks, you need to pay special attention to them.ReturnCommon Methods Generally, the return statement is the same as

Example parsing for Hook methods in Ruby and ruby hook instance Parsing By using the Hook method, we can intervene in the life cycle of Ruby classes or modules, greatly improving programming flexibility.The following hook methods related to lifecycle are available: Classes and modules Class # inherited Module # include Module # prepended Module # extend_

Let's get back to our jukebox for a moment (remember the jukebox ?). At some point We'll be working on the code that handles the user interface-the buttons that people Press to select songs and control the jukebox. We'll need to associate actions Those buttons: press START and the music starts. It turns out that Ruby's blocks are A convenient way to do this. Let's start by assuming that the people who made Hardware implemented a Ruby extension that gi

1. Debug comment Print output debugRuby is an interpreted language, a script, and on Linux, scripts cannot be executed in three ways:1. Run the script with the interpreterInterpreter script FileThat is:Ruby script File2. Run the script directlyIn the script file, use the#! Script InterpreterDefine the script interpreter path, then grant the script execute permission, then run directly./script FileCan.3. Run the script inside the interpreter[Email protected]:/home/ywt/ror_tests/ruby_tests# irb

The example explains the Hook method in Ruby and adds a hook to the method call. The example explains ruby. The Hook method is similar to the event-driven device. You can execute a specific callback function after a specific event occurs. This callback function is the hook method (more vividly described: The Hook method can be like a hook, hook up a specific event .), In Rails, The before \ after function i

Detailed description of the code block and parameter transfer in Ruby, detailed description of ruby code transfer 1. Block DeclarationAfter the function is called, the block declaration is enclosed by {...}, Or do. end encapsulation. {} Is generally used in single-line statements, and do... end is used in multi-line statements. (1 .. 4). each {| v | print "# {v}"} # output 1 2 3 4 Blocks can contain paramet