module CustomEnumerable
def my_each ()
# your code here!
for i in 0...self.length
yield(self[i])
end
end
end
class Array
include CustomEnumerable
end
[1,2,3,4].my_each { |i| puts i } # => 1 2 3 4
[1,2,3,4].my_each { |i| puts i * 10 } # => 10 20 30 40# yield calls a passed block (anonymous function) passed to the method
def some_method
puts "Before caling the block"
yield
puts "After calling the block"
end
# if a method yields and there was no block
# an error is raised
some_method #=> no block given (yield) (LocalJumpError)
# Here is a shortened syntax of passing a block
some_method { puts "Hello from the block" }
#=> Before caling the block
#=> Hello from the block
#=> After caling the block
# Here is the longer syntax of passing a block
some_method do
puts "Hello from the block"
end
# You can use the `block_given?` method to
# determine whether a block is present
def method_with_optional_block
puts "Before caling the block"
yield if block_given?
puts "After calling the block"
end
# No error is raised when no block has been passed
method_with_optional_block
#=> Before caling the block
#=> After caling the block
method_with_optional_block { puts "Hello" }
#=> Before caling the block
#=> Hello
#=> After caling the block
# You can also capture the block as a `Proc`
def method_with_proc_block(&block)
# same thing as `yield if block_given?`
block.call if block
# You can forward the passed block to another method
some_method(&block)
end