34321e4a43
This type adds an escape hatch to apps for which string duping causes unacceptable memory growth. The reason we are duping them is in order to detect mutation, which was a feature added to 4.2 in #15674. The string type was modified to support this behavior in #15788. Memory growth is really only a concern for string types, as it's the only mutable type where the act of coersion does not create a new object regardless (as we're usually returning an object of a different class). I do feel strongly that if we are going to support detecting mutation, we should do it universally for any type which is mutable. While it is less common and ideomatic to mutate strings than arrays or hashes, there shouldn't be rules or gotchas to understanding our behavior. However, I also appreciate that for apps which are using a lot of string columns, this would increase the number of allocations by a large factor. To ensure that we keep our contract, if you'd like to opt out of mutation detection on strings, you'll also be option out of mutation of those strings. I'm not completely married to the thought that strings coming out of this actually need to be frozen -- and I think the name is correct either way, as the purpose of this is to provide a string type which does not detect mutation. In the new implementation, I'm only overriding `cast_value`. I did not port over the duping in `serialize`. I cannot think of a reason we'd need to dup the string there, and the tests pass without it. Unfortunately that line was introduced at a time where I was not nearly as good about writing my commit messages, so I have no context as to why I added it. Thanks past Sean. You are a jerk. |
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| actionmailer | ||
| actionpack | ||
| actionview | ||
| activejob | ||
| activemodel | ||
| activerecord | ||
| activesupport | ||
| ci | ||
| guides | ||
| railties | ||
| tasks | ||
| tools | ||
| .gitignore | ||
| .travis.yml | ||
| .yardopts | ||
| CODE_OF_CONDUCT.md | ||
| CONTRIBUTING.md | ||
| Gemfile | ||
| Gemfile.lock | ||
| load_paths.rb | ||
| RAILS_VERSION | ||
| rails.gemspec | ||
| Rakefile | ||
| README.md | ||
| RELEASING_RAILS.md | ||
| version.rb | ||
Welcome to Rails
Rails is a web-application framework that includes everything needed to create database-backed web applications according to the Model-View-Controller (MVC) pattern.
Understanding the MVC pattern is key to understanding Rails. MVC divides your application into three layers, each with a specific responsibility.
The Model layer represents your domain model (such as Account, Product,
Person, Post, etc.) and encapsulates the business logic that is specific to
your application. In Rails, database-backed model classes are derived from
ActiveRecord::Base. Active Record allows you to present the data from
database rows as objects and embellish these data objects with business logic
methods. You can read more about Active Record in its README.
Although most Rails models are backed by a database, models can also be ordinary
Ruby classes, or Ruby classes that implement a set of interfaces as provided by
the Active Model module. You can read more about Active Model in its README.
The Controller layer is responsible for handling incoming HTTP requests and
providing a suitable response. Usually this means returning HTML, but Rails controllers
can also generate XML, JSON, PDFs, mobile-specific views, and more. Controllers load and
manipulate models, and render view templates in order to generate the appropriate HTTP response.
In Rails, incoming requests are routed by Action Dispatch to an appropriate controller, and
controller classes are derived from ActionController::Base. Action Dispatch and Action Controller
are bundled together in Action Pack. You can read more about Action Pack in its
README.
The View layer is composed of "templates" that are responsible for providing appropriate representations of your application's resources. Templates can come in a variety of formats, but most view templates are HTML with embedded Ruby code (ERB files). Views are typically rendered to generate a controller response, or to generate the body of an email. In Rails, View generation is handled by Action View. You can read more about Action View in its README.
Active Record, Active Model, Action Pack, and Action View can each be used independently outside Rails. In addition to them, Rails also comes with Action Mailer (README), a library to generate and send emails; Active Job (README), a framework for declaring jobs and making them run on a variety of queueing backends; and Active Support (README), a collection of utility classes and standard library extensions that are useful for Rails, and may also be used independently outside Rails.
Getting Started
-
Install Rails at the command prompt if you haven't yet:
gem install rails -
At the command prompt, create a new Rails application:
rails new myappwhere "myapp" is the application name.
-
Change directory to
myappand start the web server:cd myapp rails serverRun with
--helpor-hfor options. -
Using a browser, go to
http://localhost:3000and you'll see: "Welcome aboard: You're riding Ruby on Rails!" -
Follow the guidelines to start developing your application. You may find the following resources handy:
Contributing
We encourage you to contribute to Ruby on Rails! Please check out the Contributing to Ruby on Rails guide for guidelines about how to proceed. Join us!
Everyone interacting in Rails and its sub-projects' codebases, issue trackers, chat rooms, and mailing lists is expected to follow the Rails code of conduct.
Code Status
License
Ruby on Rails is released under the MIT License.