[英]ruby instance_eval will go stac level too deep when calling proc inside it
今天,我遇到了一個非常有趣的問題,紅寶石。 我有一個模塊/軌道關注:
module BreakCacheModule
extend ActiveSupport::Concern
module ClassMethods
def breakable_cache_for(method_name, &block)
method_name = method_name.to_sym
set_breakable_cache_proc(method_name, block)
define_breakable_cache_method(method_name)
end
def define_breakable_cache_method(method_name)
instance_eval(
"def #{method_name}
# here will be Rails.cache.fetch block around line below once I figure out this problem
@_break_cache_procs[#{method_name}].call # !!! this line will cause an issue
end"
)
end
def set_breakable_cache_proc(method_name, block)
@_break_cache_procs ||={}
@_break_cache_procs.merge!({method_name => block})
@_break_cache_procs
end
end
end
在我的模型中
class Client < ActiveRecord::Base
include BreakCacheModule
breakable_cache_for :all_client_ids do
Client.pluck :id
end
end
所以沙發很好,但是一旦我進入控制台(或運行我的規格),問題就會出現
Client.all_client_ids
# SystemStackError: stack level too deep
但是當我這樣做時:
Client.instance_variable_get("@_break_cache_procs")[:all_client_ids].call
#=> [1,2,3]
功能完全相同,唯一的區別是我沒有從instance_eval調用proc。
我錯過了什么嗎?
我的紅寶石ruby-2.0.0-p247和Rails 3.2.14
謝謝你的幫助
接受后更新
總結一下,我實際上從兩個地方得到了這個錯誤:
"def #{method_name}
Rails.cache.fetch(#{method_name.to_s}) do # method_name should be in quotes
@_break_cache_procs[#{method_name}].call # missing colon ...look on answer
end
end"
所以代碼應該像這樣
instance_eval(
"def #{method_name}
Rails.cache.fetch('#{method_name.to_s}') do
@_break_cache_procs[:#{method_name}].call
end
end"
)
傳遞給instance_eval
的字符串實際上是:
"def all_client_ids
@_break_cache_procs[all_client_ids].call
end"
您可能已經注意到了問題:缺少冒號。
這應該是正確的代碼:
def define_breakable_cache_method(method_name)
instance_eval(
"def #{method_name}
# here will be Rails.cache.fetch block around line below once I figure out this problem
@_break_cache_procs[:#{method_name}].call # !!! this line will cause an issue
end"
)
end
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