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
Not actually an answer to the question, but a very important consideration if you care about performance. Please notice that every time you create an OpenStruct the operation clears the method cache, which means your application will perform slower. The slowness or not of OpenStruct is not just about how it works by itself, but the implications that using them bring to the whole application: https://github.com/charliesome/charlie.bz/blob/master/posts/things-that-clear-rubys-method-cache.md#openstructs
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。
其他指标:
require 'benchmark'
require 'ostruct'
REP = 100000
User = Struct.new(:name, :age)
USER = "User".freeze
AGE = 21
HASH = {:name => USER, :age => AGE}.freeze
Benchmark.bm 20 do |x|
x.report 'OpenStruct slow' do
REP.times do |index|
OpenStruct.new(:name => "User", :age => 21)
end
end
x.report 'OpenStruct fast' do
REP.times do |index|
OpenStruct.new(HASH)
end
end
x.report 'Struct slow' do
REP.times do |index|
User.new("User", 21)
end
end
x.report 'Struct fast' do
REP.times do |index|
User.new(USER, AGE)
end
end
end
对于那些没有耐心的人来说,他们想要了解基准测试结果,而不需要自己运行它们,下面是上面代码的输出(在MB Pro 2.4GHz i7上)
user system total real
OpenStruct slow 4.430000 0.250000 4.680000 ( 4.683851)
OpenStruct fast 4.380000 0.270000 4.650000 ( 4.649809)
Struct slow 0.090000 0.000000 0.090000 ( 0.094136)
Struct fast 0.080000 0.000000 0.080000 ( 0.078940)
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.
Not actually an answer to the question, but a very important consideration if you care about performance. Please notice that every time you create an OpenStruct the operation clears the method cache, which means your application will perform slower. The slowness or not of OpenStruct is not just about how it works by itself, but the implications that using them bring to the whole application: https://github.com/charliesome/charlie.bz/blob/master/posts/things-that-clear-rubys-method-cache.md#openstructs
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
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