Rails 3 中的 Ruby 1.92：Array.length 不等于 Array.count 的情况？
我的理解是，对于 Ruby 数组，count 和 length 应该返回相同的数字。所以我无法弄清楚这里发生了什么（FactoryGirl 默认情况下设置为创建 - 保存到数据库）：
f = Factory(:family) # Also creates one dependent member
f.members.count # => 1
f.members.length # => 1
m = Factory(:member, :family=>f, :first_name=>'Sam') #Create a 2nd family member
f.members.count # => 2
f.members.length # => 1
puts f.members # prints a single member, the one created in the first step
f.members.class # => Array
f.reload
[ Now count == length = 2, and puts f.members prints both members]
我模糊地理解为什么 f 需要重新加载，尽管我预计 f. members 将涉及数据库查找具有 family_id=f.id 的成员，并且即使 f 已过时也会返回所有成员。
但计数与长度怎么会不同呢？ f.members 是一个数组，但是 count 方法是否在某处被重写，或者 Array.count 实际上返回了与 Array.length 不同的结果？不是一个紧迫的问题，只是一个谜，可能表明我对 Ruby 或 Rails 的理解存在基本缺陷。
My understanding is that count and length should return the same number for Ruby arrays. So I can't figure out what is going on here (FactoryGirl is set to create--save to database--by default):
f = Factory(:family) # Also creates one dependent member
f.members.count # => 1
f.members.length # => 1
m = Factory(:member, :family=>f, :first_name=>'Sam') #Create a 2nd family member
f.members.count # => 2
f.members.length # => 1
puts f.members # prints a single member, the one created in the first step
f.members.class # => Array
f.reload
[ Now count == length = 2, and puts f.members prints both members]
I vaguely understand why f needs to be reloaded, though I would have expected that f.members would involve a database lookup for members with family_id=f.id, and would return all the members even if f is stale.
But how can the count be different from the length? f.members is an Array, but is the count method being overridden somewhere, or is the Array.count actually returning a different result from Array.length? Not a pressing issue, just a mystery that might indicate a basic flaw in my understanding of Ruby or Rails.
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在查看源代码时， https://github.com/rails/ Rails/blob/master/activerecord/lib/active_record/associations/collection_association.rb，length 调用内部集合上的 size 方法，而 count 实际上调用数据库上的 count。
In looking at the source, https://github.com/rails/rails/blob/master/activerecord/lib/active_record/associations/collection_association.rb, length calls the size method on the internal collection and count actually calls count on the database.