CODEWITHSUNDEEP
ruby
slindsey3000
slindsey3000

Reputation: 4271

Is there any way to pass an integer into a method chain?

Example:

7.cars.2.doors

I will add the cars method to Integer and it will return a CarBuilding object.

This CarBuilding object then needs to receive the message 2 which will do some processing and return itself.

Finally doors will be called on this CarBuilding object

Any kind of fancy Meta Programming able to do this?

Note: I don't want to pass parameters. Just use method chaining.

Upvotes: 0

Views: 87

Answers (2)

SergA
SergA

Reputation: 1174

Because names started with digit are not valid you can use underscore:

class CarBuilding
  def method_missing(method, *args, &block)
    raise NoMethodError unless method =~ /\A_\d*\z/
    puts "do something with #{method[1..-1].to_i}"
    return self
  end
  def doors
    puts "doors"
  end
end

class Integer
  def cars
    return CarBuilding.new
  end
end

puts 7.cars._2.doors

Upvotes: 1

Jörg W Mittag
Jörg W Mittag

Reputation: 369458

No, this isn't possible.

Using normal message sending syntax, the message must be a valid identifier. 2 is not a valid identifier, identifiers can't start with a digit. This is simply not syntactically legal.

It is possible to define a method named 2 using metaprogramming. Note, however, that this is the name 2 and not the Integer 2. Obviously, it is not possible to invoke such a method using normal message sending syntax (nor is it possible to define it using normal method definition syntax).

class CarBuilding
  define_method(:'2') do
    CarBuildingWithDoors.new(2)
  end
end

7.cars.public_send(:'2').doors

Upvotes: 3

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