Skip to content
This repository
tag: v4.0.0.beta1
Fetching contributors…

Cannot retrieve contributors at this time

file 78 lines (75 sloc) 2.148 kb
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78
class Object
  # Invokes the public method whose name goes as first argument just like
  # +public_send+ does, except that if the receiver does not respond to it the
  # call returns +nil+ rather than raising an exception.
  #
  # This method is defined to be able to write
  #
  # @person.try(:name)
  #
  # instead of
  #
  # @person ? @person.name : nil
  #
  # +try+ returns +nil+ when called on +nil+ regardless of whether it responds
  # to the method:
  #
  # nil.try(:to_i) # => nil, rather than 0
  #
  # Arguments and blocks are forwarded to the method if invoked:
  #
  # @posts.try(:each_slice, 2) do |a, b|
  # ...
  # end
  #
  # The number of arguments in the signature must match. If the object responds
  # to the method the call is attempted and +ArgumentError+ is still raised
  # otherwise.
  #
  # If +try+ is called without arguments it yields the receiver to a given
  # block unless it is +nil+:
  #
  # @person.try do |p|
  # ...
  # end
  #
  # Please also note that +try+ is defined on +Object+, therefore it won't work
  # with instances of classes that do not have +Object+ among their ancestors,
  # like direct subclasses of +BasicObject+. For example, using +try+ with
  # +SimpleDelegator+ will delegate +try+ to the target instead of calling it on
  # delegator itself.
  def try(*a, &b)
    if a.empty? && block_given?
      yield self
    else
      public_send(*a, &b) if respond_to?(a.first)
    end
  end

  # Same as #try, but will raise a NoMethodError exception if the receiving is not nil and
  # does not implemented the tried method.
  def try!(*a, &b)
    if a.empty? && block_given?
      yield self
    else
      public_send(*a, &b)
    end
  end
end

class NilClass
  # Calling +try+ on +nil+ always returns +nil+.
  # It becomes specially helpful when navigating through associations that may return +nil+.
  #
  # nil.try(:name) # => nil
  #
  # Without +try+
  # @person && !@person.children.blank? && @person.children.first.name
  #
  # With +try+
  # @person.try(:children).try(:first).try(:name)
  def try(*args)
    nil
  end

  def try!(*args)
    nil
  end
end
Something went wrong with that request. Please try again.