我不知道这是一个哈希问题还是数组问题,但我不明白为什么在第三个示例中需要使用星号(*)符号来获取填充数据的散列。没有它,它会输出一个空的散列。为什么在数组之前需要星号?
# -*- coding: utf-8 -*-
require 'pp'
pp [[:first_name, 'Shane'], [:last_name, 'Harvie']]
# => [[:first_name, "Shane"], [:last_name, "Harvie"]]
pp [[:first_name, 'Shane'], [:last_name, 'Harvie']].flatten
# => [:first_name, "Shane", :last_name, "Harvie"]
pp Hash[*[[:first_name, 'Shane'], [:last_name, 'Harvie']].flatten]
# => {:first_name=>"Shane", :last_name=>"Harvie"}
pp Hash[[[:first_name, 'Shane'], [:last_name, 'Harvie']].flatten]
# => {}
下面是该方法的说明。
--------------------------------------------------------------- Hash::[]
Hash[ [key =>|, value]* ] => hash
From Ruby 1.8
------------------------------------------------------------------------
Creates a new hash populated with the given objects. Equivalent to
the literal +{ _key_, _value_, ... }+. Keys and values occur in
pairs, so there must be an even number of arguments.
Hash["a", 100, "b", 200] #=> {"a"=>100, "b"=>200}
Hash["a" => 100, "b" => 200] #=> {"a"=>100, "b"=>200}
{ "a" => 100, "b" => 200 } #=> {"a"=>100, "b"=>200}
非常感谢您的详细解释和链接。现在我完全明白这是什么。现在一切都很有意义。 – 2009-12-12 15:48:13