一般来说,与Struct相比,使用OpenStruct的优点和缺点是什么?什么样类型的通用用例适合每一个?


当前回答

与Structs相比,OpenStructs使用的内存明显更多,运行速度更慢。

require 'ostruct' 

collection = (1..100000).collect do |index|
   OpenStruct.new(:name => "User", :age => 21)
end

在我的系统上,以下代码在14秒内执行,消耗了1.5 GB内存。你的里程可能有所不同:

User = Struct.new(:name, :age)

collection = (1..100000).collect do |index|
   User.new("User",21)
end

这几乎是在瞬间完成的,消耗了26.6 MB的内存。

其他回答

与Structs相比,OpenStructs使用的内存明显更多,运行速度更慢。

require 'ostruct' 

collection = (1..100000).collect do |index|
   OpenStruct.new(:name => "User", :age => 21)
end

在我的系统上,以下代码在14秒内执行,消耗了1.5 GB内存。你的里程可能有所不同:

User = Struct.new(:name, :age)

collection = (1..100000).collect do |index|
   User.new("User",21)
end

这几乎是在瞬间完成的,消耗了26.6 MB的内存。

结构:

>> s = Struct.new(:a, :b).new(1, 2)
=> #<struct a=1, b=2>
>> s.a
=> 1
>> s.b
=> 2
>> s.c
NoMethodError: undefined method `c` for #<struct a=1, b=2>

OpenStruct:

>> require 'ostruct'
=> true
>> os = OpenStruct.new(a: 1, b: 2)
=> #<OpenStruct a=1, b=2>
>> os.a
=> 1
>> os.b
=> 2
>> os.c
=> nil

使用@Robert代码,我将Hashie::Mash添加到基准测试项中,得到了这样的结果:

                           user     system      total        real
Hashie::Mash slow      3.600000   0.000000   3.600000 (  3.755142)
Hashie::Mash fast      3.000000   0.000000   3.000000 (  3.318067)
OpenStruct slow       11.200000   0.010000  11.210000 ( 12.095004)
OpenStruct fast       10.900000   0.000000  10.900000 ( 12.669553)
Struct slow            0.370000   0.000000   0.370000 (  0.470550)
Struct fast            0.140000   0.000000   0.140000 (  0.145161)

使用OpenStruct,您可以任意创建属性。另一方面,Struct必须在创建时定义其属性。选择一种还是另一种应该主要基于您以后是否需要能够添加属性。

The way to think about them is as the middle ground of the spectrum between Hashes on one side and classes on the other. They imply a more concrete relationship amongst the data than does a Hash, but they don't have the instance methods as would a class. A bunch of options for a function, for example, make sense in a hash; they're only loosely related. A name, email, and phone number needed by a function could be packaged together in a Struct or OpenStruct. If that name, email, and phone number needed methods to provide the name in both "First Last" and "Last, First" formats, then you should create a class to handle it.

看一下与新方法相关的API。这里有很多不同之处。

就我个人而言,我非常喜欢OpenStruct,因为我不需要预先定义对象的结构,只需要添加我想要的东西。我猜这将是它的主要(缺点)优势?

http://www.ruby-doc.org/core/classes/Struct.html http://www.ruby-doc.org/stdlib/libdoc/ostruct/rdoc/classes/OpenStruct.html