to_a和to_ary有什么区别？-What'sthedifferencebetweento_aandto_ary?

40  

to_ary is used for implicit conversions, while to_a is used for explict conversions.

to_ary用于隐式转换，而to_a用于explict转换。

For example:

例如：

class Coordinates
  attr_accessor :x, :y

  def initialize(x, y); @x, @y = x, y end

  def to_a; puts 'to_a called'; [x, y] end

  def to_ary; puts 'to_ary called'; [x, y] end

  def to_s; "(#{x}, #{y})" end

  def inspect; "#<#{self.class.name} #{to_s}>" end
end

c = Coordinates.new 10, 20
# => #

The splat operator (*) is a form of explicit conversion to array:

splat运算符（*）是一种显式转换为数组的形式：

c2 = Coordinates.new *c
# to_a called
# => #

On the other hand, parallel assignment is a form of implicit conversion to array:

另一方面，并​​行赋值是一种隐式转换为数组的形式：

x, y = c
# to_ary called
puts x
# 10
puts y
# 20

And so is capturing collection members in block arguments:

在块参数中捕获集合成员也是如此：

[c, c2].each { |(x, y)| puts "Coordinates: #{x}, #{y}" }
# to_ary called
# Coordinates: 10, 20
# to_ary called
# Coordinates: 10, 20

Examples tested on ruby-1.9.3-p0.

在ruby-1.9.3-p0上测试的实施例。

This pattern seems to be used all over the Ruby language, as evidenced by method pairs like to_s and to_str, to_i and to_int and possibly more.

这种模式似乎在整个Ruby语言中使用，如to_s和to_str，to_i和to_int等可能更多的方法对所证明。

References:

参考文献：

• Ruby Issue 3680
• Ruby Issue 3680
• Variables
• 变量

19  

to_ary allows an object to be treated as an array, whereas to_a actually tries to convert the parameter into an array.

to_ary允许将对象视为数组，而to_a实际上尝试将参数转换为数组。

to_ary can be useful for parallel assignment, whereas to_a is more suited for an actual conversion.

to_ary对并行赋值很有用，而to_a更适合实际转换。

12  

Quoted from gabew's web space:

引自gabew的网络空间：

Calling #to_a will convert the receiver to an Array, while #to_ary will not.

调用#to_a会将接收器转换为数组，而#to_ary则不会。

ruby-1.9.2-p290 :001 > class A  A[].to_a.class
 => Array

ruby-1.9.2-p290 :005 > A[].to_ary.class
 => A 

0  

to_a, when called on an object returns an array representation of obj

to_a，当在一个对象上调用时，返回一个obj的数组表示

Examples

例子

class Example
  def initialize
      @str = 'example'
  end
end

a = Example.new #=> # [#]

Hash Example

哈希示例

h = { "c" => 300, "a" => 100, "d" => 400, "c" => 300  } 
h.to_a   #=> [["c", 300], ["a", 100], ["d", 400]]

An array can also be created by using the Array() method, provided by Kernel, which tries to call to_ary, then to_a on its argument. http://ruby-doc.org/core-2.0/Array.html#method-i-to_ary

也可以使用由Kernel提供的Array（）方法创建一个数组，该方法尝试调用to_ary，然后调用to_a的参数。 http://ruby-doc.org/core-2.0/Array.html#method-i-to_ary

so as far as I can see, the Array#to_ary src just returns the array that is passed in, as in

所以我可以看到，Array＃to_ary src只返回传入的数组，如

def to_ary
  return self
end

if I understand correctly, to_a is used for array conversion and makes its final return using to_ary. But this may not be true in future versions according to apidock

如果我理解正确，to_a用于数组转换并使用to_ary进行最终返回。但根据apidock的说法，未来的版本可能并非如此

to_a Returns an array representation of obj. For objects of class Object and others that don’t explicitly override the method, the return value is an array containing self. However, this latter behavior will soon be obsolete. http://apidock.com/ruby/Object/to_a

to_a返回obj的数组表示形式。对于Object类的对象和其他未显式覆盖该方法的对象，返回值是一个包含self的数组。但是，后一种行为很快就会过时。 http://apidock.com/ruby/Object/to_a