Why is Ruby more suitable for Rails than Python? [closed]

Question

Python and Ruby are usually considered to be close cousins (though with quite different historical baggage) with similar expressiveness and power. But some have argued that the immense success of the Rails framework really has a great deal to do with the language it is built on: Ruby itself. So why would Ruby be more suitable for such a framework than Python?

Answer 1

There are probably two major differences:

Ruby has elegant, anonymous closures.

Rails uses them to good effect. Here's an example:

class WeblogController < ActionController::Base   def index     @posts = Post.find :all     respond_to do |format|       format.html       format.xml { render :xml => @posts.to_xml }       format.rss { render :action => "feed.rxml" }     end   end end 

Anonymous closures/lambdas make it easier to emulate new language features that would take blocks. In Python, closures exist, but they must be named in order to be used. So instead of being able to use closures to emulate new language features, you're forced to be explicit about the fact that you're using a closure.

Ruby has cleaner, easier to use metaprogramming.

This is used extensively in Rails, primarily because of how easy it is to use. To be specific, in Ruby, you can execute arbitrary code in the context of the class. The following snippets are equivalent:

class Foo   def self.make_hello_method     class_eval do       def hello         puts "HELLO"       end     end   end end  class Bar < Foo # snippet 1   make_hello_method end  class Bar < Foo; end # snippet 2 Bar.make_hello_method 

In both cases, you can then do:

Bar.new.hello   

which will print "HELLO". The class_eval method also takes a String, so it's possible to create methods on the fly, as a class is being created, that have differing semantics based on the parameters that are passed in.

It is, in fact, possible to do this sort of metaprogramming in Python (and other languages, too), but Ruby has a leg up because metaprogramming isn't a special style of programming. It flows from the fact that in Ruby, everything is an object and all lines of code are directly executed. As a result, Classes are themselves objects, class bodies have a self pointing at the Class, and you can call methods on the class as you are creating one.

This is to large degree responsible for the degree of declarativeness possible in Rails, and the ease by which we are able to implement new declarative features that look like keywords or new block language features.

Answer 2

Those who have argued that

the immense success of the Rails framework really has a great deal to do with the language it is built on

are (IMO) mistaken. That success probably owes more to clever and sustained marketing than to any technical prowess. Django arguably does a better job in many areas (e.g. the built-in kick-ass admin) without the need for any features of Ruby. I'm not dissing Ruby at all, just standing up for Python!