Jul 25, 2009 is the ruby communitys gem hosting service. The confident ruby companion screencast more watch over my shoulder as i apply concepts and patterns from the book to the discourse codebase. Now take it to the next level with eval, object lifecycle hooks, and more. Awesome print works with irb as well as pry, but for the time being, we. Ruby metaprogramming, one of the most interesting aspects of ruby, enables the programming language to achieve an extreme level of expressiveness. Dig under the surface and explore ruby s most advanced feature. This pdf file contains pages extracted from metaprogramming ruby, published by the.
Once you understand the principles of ruby, including the object model, scopes, and eigenclasses, youre on your way to applying metaprogramming both in your daily work and in your fun, afterhours projects. This tutorial will provide stepbystep instructions for generating pdfs with very little effort by using wkhtmltopdf. Rubys object model is the land in which metaprogramming. For those that might now know irb is the ruby repl distributed with mri, and written in ruby. You can write simple class methods which will add class methods to a derived class.
Before we ride on rails, let us recapitulate a few points of ruby, which is the base of rails. Program like the ruby pros kindle edition by perrotta, paolo. Download it once and read it on your kindle device, pc, phones or tablets. Pragmatic examples of metaprogramming in action, many of which come straight from reallife gems such as rails. For gem authors and application developers alike, this book lays down the. Awesome print works with irb as well as pry, but for the time being, we will be focused on the irb code path. The following chapters tell the story of a week in the life of a newly hired ruby programmer and his or her more experienced colleague. Metaprogramming ruby, second edition makes mastering the language enjoyable. Rails makes heavy use of metaprogramming, so its a good place to start looking. Collection of metaprogrammingrelated small snippets. The book goes into considerable depth on how it works, and presents many examples of manipulating the object model to good use. One aspect of metaprogramming that ruby excels at is being able to ask our code.
A good example is the dynamic finder methods in activerecord like. This is the secret to rails and ruby x11 and so many other examples of metaprogramming in ruby. Using java alone would now feel like entering a sword. Become a contributor and improve the site yourself. What readers are saying about metaprogramming ruby reading this book was like diving into a new world of thinking. To start off, lets look at the wikipedia definition. Metaprogramming is the writing of computer programs with the ability to treat programs as their data.
Paolo describes metaprogramming in a fun and approachable way for all skill levels. Add more powerful abstractions and reduce duplication through ruby that writes ruby. This last is pretty important, because metaprogramming is arguably one of the most misused features of the ruby language. Everyday low prices and free delivery on eligible orders. When doing any metaprogramming, tracking changes to the runtime is a problem that you will encounter sooner or later. Program like the ruby pros facets of ruby 1 by paolo perrotta isbn. This pdf file contains pages extracted from metaprogramming ruby. Metaprogramming ruby for greater good jarkko wrote this on sep 29th, 2014 11. The pdfkitsave pdf header is never sent back to the client. Metaprogramming ruby 2 program like the ruby pros paolo perrotta the pragmatic bookshelf dallas, texas raleigh, north carolina. Now see how to unleash its power, digging under the surface and exploring the languages most advanced features. Aug 29, 2011 welcome back to metaprogramming with ruby. The base class in ruby is called object or basicobject in ruby 1.
The round method will round a number up if the first digit after its decimal place is 5 or higher and round down if that digit is 4 or lower. Activerecord is part of rails, the quintessential ruby framework. Program like the ruby pros metaprogramming ruby 2nd edition metaprogramming ruby second edition rails 4 ruby 1. Ruby s object model is the land in which metaprogramming. The focus of this book is to demonstrate how metaprogramming happens in ruby, what its limitations are and what kinds of problems are best solved using it. Specialising dynamic techniques for implementing the ruby. In ruby everything is an object, strings, integers, even functions. It provides programmatic access to the contents of a pdf file with a high degree of flexibility. In part one we looked at what metaprogramming is and how it works. Dont let this abstract definition scare you away though, because ruby makes metaprogramming as easy to understand as it is to work with. Rails relies heavily on metaprogramming to make the interface as intuitive as it is, without reams of code to catch every possible scenario. Starting off the list for examples of metaprogramming is monkey patching. Implementing metaprogramming techniques can drastically eliminate duplicate code, making your applications far easier to maintain and build. This pdf file contains pages extracted from metaprogramming ruby 2, published by the pragmatic bookshelf.
The dynamic nature of ruby makes it really easy to do metaprogramming. Program like the ruby pros pdf, epub, docx and torrent then this site is not for you. The first method in this class is a class method and the second one is an instance method. Monkey patching is an object oriented programming technique that allows developers to. It is worth pointing out that the class test itself is actually an object. Once the domain of expert rubyists, metaprogramming is. For gem authors and application developers alike, this book lays down the foun dation everyone needs to harness the full power of ruby. There are many ways to generate a pdf in ruby on rails, with the best approach really depending on the types of pdfs you need to generate. With metaprogramming, you can produce elegant, clean, and beautiful programs. Ruby inherits characteristics from various languageslisp, smalltalk, c, and perl, to name a few. If youre looking for a free download links of metaprogramming ruby. We expect answers to be supported by facts, references, or expertise, but this question will likely solicit debate, arguments.
Ruby book free download, ruby book free pdf, ruby free pdf book, ruby free book, ruby books for beginners, ruby books pdf, ruby books,books to learn ruby,books to learn. Jruby metaprogramming ruby metaprogramming ruby 2 metaprogramming ruby 2. Metaprogramming ruby 2 program like the ruby pros by paolo perrotta. Jun 26, 2006 metaprogramming, defined as writing code that writes code by why the lucky stiff, makes scaffolding, associations, validations, and the many magical parts of rails possible. This book describes metaprogramming as an essential component of ruby. However, this is causing some problems because when the gem is included in a project, its trying to query role before activerecord has established a connection, resulting in an exception being thrown. Metaprogramming ruby 2 program like the ruby pros ruby inherits characteristics from various languageslisp, smalltalk, c, and perl, to name a few. Ruby offers programmers what are called object lifecycle callbacks to track such changes and respond to them. Many gems make use of this to add additional functionality to existing code. Metaprogramming the missing semester of your cs education. Erb allows you to put ruby codes inside an html file. If youre looking for a free download links of metaprogramming ruby 2.
Rubys metaprograming is the key feature that makes rails magical. Program like the ruby pros facets of ruby perrotta. Ruby on rails sql this modified text is an extract of the original stack overflow documentation created by following contributors and released under cc bysa 3. Program like the ruby pros facets of ruby by paolo perrotta metaprogramming ruby 2. Modern programming languages provide extensive metaprogramming facilities. An adventure in metaprogramming more this bonus ebook follows the stepbystep, testdriven development of the naught gem for constructing null object classes. In this book, youll learn metaprogramming as an essential component of ruby and discover the deep, nonobvious details of the language. Write powerful ruby code that is easy to maintain and change. It is because of this very feature that many gems, such as rspec and activerecord, can work the way they do.
Read metaprogramming ruby 2 pdf program like the ruby pros facets of ruby pdf metaprogramming ruby 2 ebook by paolo perrotta pdf get metaprogramming r slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. Part ii of the book, metaprogramming in rails, is a case study in metaprogram ming. Metaprogramming ruby program like the ruby pros by paolo perrotta. As the book progresses, these concepts assimilate into larger concepts, and the. Use features like bookmarks, note taking and highlighting while reading metaprogramming ruby. Ruby for metaprogramming closed ask question asked 11 years, 2 months ago. For more information or to purchase a paperback or pdf copy. Once the domain of expert rubyists, metaprogramming is now accessible to. Erb reads along, word for word, and then at a certain point, when it.
Ability to create classes, methods, functions, etc. Pdftoimage is a ruby gem which allows for conversion of a pdf document into images. Its very easy to extend and modify existing primitives at runtime. Awesome print is a gem for pretty printing ruby objects.
The example section shows how to apply the pattern in the specific context of. Metaprogramming is writing code that writes code during runtime to make your life easier. Text content is released under creative commons bysa. It comes down to the fact that all ruby code is executed codethere is no separate compile or runtime phase. After writing my last post on rails plugin idioms, i realized that ruby metaprogramming, at its core, is actually quite simple. Yes, its a weird name, but its a powerful and dangerous tool. In development environments it is common to run a single server process. This can cause issues when rendering your pdf requires. In this article, toptal engineer nikola todorovic demystifies. Ruby metaprogramming ruby is a very flexible language. When hes not writing code hes usually weightlifting. Preferably, minimal distinction between code and data, lisp style.
Program like the ruby pros facets of ruby pdf, epub, docx and torrent then this site is not for you. I can simply move the metaprogramming to an initializer or something, but then it has to be repeated in every application that uses the gem. The pdfreader library implements a pdf parser conforming as much as possible to the pdf specification from adobe. Metaprogramming ruby for greater good by jarkko of bear metal. In this workshop, well learn some of the very basics of metaprogramming in ruby. Presentation mode open print download current view. Another aspect of metaprogramming that ruby gives us is the ability to generate new code during runtime. I tried a mix of java and jruby metaprogramming on a recent project. Youve learned the basics of writing code with code in metaprogramming ruby. Learning metaprogramming doesnt have to be difficult or boring. Once you understand the tenets of ruby, including the object model, scopes, and singleton classes, youre on your way to applying.
The ruby notes for professionals book is compiled from stack overflow documentation, the content is written by the beautiful people at stack overflow. In this lecture, we will look at systems for building and. Code that writes code epilogue metaprogramming in rails the design of activerecord inside. Part i, metaprogramming ruby, is the core of the book. Say you want to write a ruby program that connects to an external systemmaybe a web service or a java program. This pdf file contains pages extracted from metaprogramming ruby 2. I discovered most of this while building dwemthys array for my cartoon ruby book. Here are some of the things you can do with metaprogramming in the ruby language. Nov 15, 2009 after writing my last post on rails plugin idioms, i realized that ruby metaprogramming, at its core, is actually quite simple. Metaprogramming ruby 2 program like the ruby pros ruby inherits characteristics from various languageslisp, smalltalk, c, and perl, to name a. Program like the ruby pros facets of ruby by paolo perrotta write powerful ruby code that is easy to maintain and change.
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