Classify a Ruby string | 易学教程

问题

I have a program that create classes which looks like:

  MyClass = Class.new do
    def initialize; end
    # ...
  end

But I would like to name dynamically MyClass, from a string. And because it's for the name of a class, I would like to classify that string, for instance (thanks Rails methods):

  "hello_world".classify # => "HelloWorld"

I don't know if in pure Ruby there is a method for that.

Thank you

回答1:

Not sure if your question is only about constructing a camelcased string, or also about assigning a newly created class to it. Because, for the latter, you should use Module::const_set method:

class_name = 'MyClass'
#=> "MyClass"
klass = Class.new do
  def foo
    "foo"
  end
end
#=> #<Class:0xa093a68>
Object.const_set class_name, klass
#=> Module::MyClass
MyClass.new.foo
#=> "foo"

回答2:

No, there isn't. Here's the String reference page.

You could do so like this:

"hello_world".split('_').collect!{ |w| w.capitalize }.join

You could easily implement this by reclassing the String class.

However, if you're using Rails for whatever reason, classify is added for convenience, along with the underscore method. I believe it's still used in Rails 3.

回答3:

If you wanted just to access the class from a string name, and not define it from a string, you can also use this:

MyClass = Class.new do
    def test; end
    # ...
end
"MyClass".constantize.test # => what you wanted ?

回答4:

This is much later, but I am going through this process and expanding on mway's answer I am using this:

class String
  def classify
    self.split('/').collect do |c|
      c.split('_').collect(&:capitalize).join
    end.join('::')
  end
end

This will allow you to add namespaces to strings. So:

"api/post_comments".classify
=> "Api::PostComments"

来源：https://stackoverflow.com/questions/4072159/classify-a-ruby-string

标签

ruby

string

metaprogramming