RAILS SIMPLY FEELS RIGHT 20
Rails applications are written in Ruby, a modern, object-oriented scripting
language. Ruby is c oncise without being unintelligibly terse—you can express
ideas naturally and cleanly in Ruby code. This leads to pr ogra ms that are easy
to write and (just as important) are easy to read months later.
Rails takes Ruby to the limit, extending it in novel ways that make a pro-
grammer’s life easier. This makes our programs shorter and more readable.
It also allows us to perform tasks that would normally be done in external
configuration files inside the codebase instead. This makes it far easier to see
what’s happening. The following code defines the model class for a project.
Don’t worry about the details for now. Instead, just think about how much
information is being expressed in a few lines of code.
class Project < ActiveRecord::Base
belongs_to :portfolio
has_one :project_manager
has_many :milestones
has_many :deliverables, :through => :milestones
validates :name, :description, :presence =>
true
validates :non_disclosure_agreement, :acceptance => true
validates :short_name, :uniqueness => true
end
Two other philosophical underpinnings keep Rails code short and readable:
DRY and convention over configuration. DRY stands for don’t repeat yourself :
every piece of knowledge in a system should be expr essed in just one place.
Rails uses the power of Ruby to bring that to life. You’ll find very little duplica-
tion in a Rails application; you say what you need to say in one place—a place
often suggested by the conventions of the MVC architecture—and then move
on. For programmers used to other web frameworks, where a simple change
to the schema could involve them in half a dozen or more code changes, this
was a revelation.
Convention over configuration is crucial, too. It means that Rails has sensi-
ble defaults for just about every aspect of knitting together your application.
Follow the conventions, and you can write a Rails application using less code
than a ty pical Java web application uses in XML configuration. If you need to
override the conventions, Rails makes that easy, too.
Developers coming to Rails found something else, too. Rails isn’t playing catch-
up with the new de facto web standards; it’s helping define them. And Rails
makes it easy for developers to integrate features such as Ajax and RESTful
interfaces into their code, because support is built in. (And if you’re not famil-
iar with Ajax and REST interfaces, never fear—we’ll explain them later in the
book.)
Report erratum
this copy is (B8.0 printing, September 9, 2010)
Prepared exclusively for Jared Rosoff
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