k2works

# coding: utf-8
class Foo
end

foo = Foo.new
bar = Foo.new

# barだけにメソッドを定義する
def bar.singleton_method
   puts 'Called!'

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class OriginalClass
end

obj = OriginalClass.new

def obj.new_singleton_method
   :new_singleton_method
end

obj.class.method_defined? :new_singleton_method # => false

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module ExtendedModule
   def extend_method
	  :extend_method
   end
end

obj = Object.new
obj.extend ExtendedModule

obj.extend_method 				# => :extend_method

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class LoggingInstanceVariable
   logging_instance_val_names = %w(first_val second_val third_val)

   logging_instance_val_names.each do |val_name| 
	  eval <<-END_OF_DEF
        attr_reader :#{val_name}, :before_#{val_name}

        def #{val_name}=(val)
          @before_#{val_name} = @#{val_name}
          @#{val_name} = val

k2works

class AttrClass
   def initialize
	  @attr = "attr"
   end

   def add_reader(instance_val_name)
	  eval <<-END_OF_DEF
        def #{instance_val_name}
          @#{instance_val_name}
        end

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class EvalTarget
   def initialize
	  @instance_val = 'instance valiable'
   end

   def instance_binding
	  local_val = 'local valiable' # !> assigned but unused variable - local_val
	  binding
   end

k2works

# coding: utf-8
def create_proc
   str = 'from create_proc'
   Proc.new { str }
end

proc_obj = create_proc

str = 'from toplevel'  
# proc_obj内で呼び出されるstrの参照はcreate_proc内のstrになっている

k2works

# coding: utf-8
require 'csv'

data = <<EOS
name,age,gender
alice,14,female
bob,32,male
carol,17,female
EOS

k2works

require 'csv'

converter = ->(field,field_info) {
   if field_info.index == 1
	  field.upcase rescue field
   else
	  field
   end  
}

k2works

require 'csv'

headers = %w(name age gender)
people = [
   ['alice',14,'female'],
   ['bob',32,'unknown'],
   ['carol',17,'female']   
]

csv_string = CSV.generate('', write_headers: true, headers: headers) { |csv|