Leon's Blogging

Coding blogging for hackers.

Ruby - Array With Default Value

| Comments

Array.new 可以建立一個長度的 default value

這樣建立的話會對應到一樣的 object

1
2
3
4
5
6
7

a = Array.new(2, Hash.new) # => [{}, {}]

a[0]['animal'] = 'dog' # => "dog"
a # => [{"animal"=>"dog"}, {"animal"=>"dog"}]

a[1]['animal'] = 'cat' # => "cat"
a # => [{"animal"=>"cat"}, {"animal"=>"cat"}]

必須給 block 每個 object 才會是獨立的

1
2
3

a = Array.new(2) { Hash.new } # => [{}, {}]
a[0]['animal'] = 'dog' # => "dog"
a # => [{"animal"=>"dog"}, {}]

參考文件

Comments