TIL: Ruby and Rails knowledges 1

What I Learned

Couple of months of Rails experience, I summarazie something that I learned from ruby, rails's useful things.

Safe Navigation Operator.

Introduced in Ruby 2.3.0, (Avoiding an undefined method for nil:NilClass error), similar to the try method in Rails.

So you can write

user&.address&.zip

instead of

if user
  user.address.zip
else
  nil
end

Alternatives

When only the first item in a chain is nullable, we can use && instead of &. to more accurately express our intention.

user && user.address.zip

Beyond just using different syntax, there is also an opportunity to refactor. The chain of non-nullable methods can safely be extracted out. This likely results in cleaner code and also satisfies the law of demeter.

class User
  def zip
    address.zip
  end
end

Dynamically define method

Defines an instance method in the receiver. The method parameter can be a Proc, a Method or an UnboundMethod object. If a block is specified, it is used as the method body.

from apidock

class Product
  class << self
    [:name, :brand].each do |attribute|
      define_method :"find_by_#{attribute}" do |value|
        all.find {|prod| prod.public_send(attribute) == value }
      end
    end
  end
end

Ruby freeze

freeze()

Prevents further modifications to obj. A RuntimeError will be raised if modification is attempted. There is no way to unfreeze a frozen object. See also Object#frozen?.

from apidock

str = "this is string"
str.freeze

str.replace("this is new string") #=> FrozenError (can't modify frozen String)
or
str[0] #=> 't'
str[0] = 'X' #=> FrozenError (can't modify frozen String)

Retrospect

Actually JS have similary like Ruby Safe Navigation. But define method is super nice for specific case. Like factory pattern. and easy-to-use pattern. Also Freeze can be found in many language. But What I learned is to handle literals in class. In JS, I think I used enums. but It was not that smooth sometimes. These are small part of ruby and I'm still getting used to them. I hope I can write ruby & rails fluently while following the community's rules.

Well Done !