ruby method block and yield

gistfile1.rb

# In Ruby, you can always pass a block to a method call.

def foo
end

# Call foo with a block, but foo just ignores the block
foo { puts "doesn't call the block" }

# foo can capture the block

def foo(&block)
  # still doesn't do anything with the block
end

# foo can call the captured block

def foo(&block)
  block.call
end

# yield is a more efficient way to do the same as above

def foo
  yield
end

# the following two are equivalent

def foo(&block)
  !block.nil? && block.call
end

def foo
  yield if block_given?
end