ruby block问题
做七周七语言ruby第二天习题的时候要实现一个简单的Tree类，以下代码可以运行，但是把children.each {|c| c.visit_all(n+1) {|node| puts "-#{node.node_name}"}}
这行的{|node| puts "-#{node.node_name}"}改成&block就跑不起来，请问是为什么？
#!/usr/bin/ruby
class Tree
attr_accessor :children,:node_name
def initialize(tree)
tree.each do |key,value|
@node_name = key
@children = value.map {|(key,value)| Tree.new(key => value)}
end
end
def visit_all(n,&block)
visit &block
print ' ' * n
children.each {|c| c.visit_all(n+1) {|node| puts "-#{node.node_name}"}}
end
def visit(&block)
block.call self
end
end
ruby_tree = Tree.new({
'grandpa' => {
'day' => {'child 1' => {},'child 2' => {}},'uncle' => {'child 3' => {},'child 4' => {}}
}
})
ruby_tree.visit_all(1) {|node| puts "-#{node.node_name}"}
ps: ruby环境是2.1.3
