Obtaining the same types and reducing symbol length

Obtaining the same types and reducing symbol length 獲得相同類型以及縮短符號長度

The flexible option specification mechanism used by Boost.Intrusive for hooks and containers has a couple of downsides:
Boost.Intrusive 對鉤子和容器所使用的靈活的選項說明機制有兩個缺點：

If a user specifies the same options in different order or specifies some options and leaves the rest as defaults, the type of the created container/hook will be different. Sometimes this is annoying, because two programmers specifying the same options might end up with incompatible types. For example, the following two lists, although using the same options, do not have the same type:
如果以不同的順序指定相同的選項，或者指定一些選項而保留其它選項為缺省值，那麼所創建的容器/鉤子將是不同的。有時候這是很討厭的，因為兩個指定了相同選項的程序員可能最終得到的是不兼容的類型。例如，以下兩個鏈表雖然使用了相同的選項，卻不是相同的類型：

#include <boost/intrusive/list.hpp>

using namespace boost::intrusive;

//Explicitly specify constant-time size and size type 顯式指定常量時間的 size 和 size 類型
typedef list<T, constant_time_size<true>, size_type<std::size_t> List1;

//Implicitly specify constant-time size and size type 隱式指定常量時間的 size 和 size 類型 
typedef list<T> List2;

Option specifiers lead to long template symbols for classes and functions. Option specifiers themselves are verbose and without variadic templates, several default template parameters are assigned for non-specified options. Object and debugging information files can grow and compilation times may suffer if long names are produced.
選項規格說明導致了類和函數的超長模板符號。選項規格說明本身是冗長的且無變長模板的，對於未指定的選項要賦予缺省的模板參數。如果產生了長名字，那麼目標文件和調試信息文件會變大，編譯時間也會變久。

To solve these issues Boost.Intrusive offers some helper metafunctions that reduce symbol lengths and create the same type if the same options (either explicitly or implicitly) are used. These also improve compilation times. All containers and hooks have their respective make_xxx versions. The previously shown example can be rewritten like this to obtain the same list type:
為解決這些問題，Boost.Intrusive 提供了一些輔助元函數來縮短符號長度，並且在使用相同選項(不論顯式或隱式)時創建相同的類型。這樣也可以加快編譯的時間。所有的容器和鉤子都具有各自的 make_xxx 版本。前面所示的例子可以如下重寫，以獲得相同的 list 類型：

#include <boost/intrusive/list.hpp>

 using namespace boost::intrusive;

 #include <boost/intrusive/list.hpp>

 using namespace boost::intrusive;

 //Explicitly specify constant-time size and size type 顯式指定常量時間的 size 和 size 類型 
 typedef make_list<T, constant_time_size<true>, size_type<std::size_t>::type List1;

 //Implicitly specify constant-time size and size type 隱式指定常量時間的 size 和 size 類型 
 typedef make_list<T>::type List2;

Produced symbol lengths and compilation times will usually be shorter and object/debug files smaller. If you are concerned with file sizes and compilation times, this option is your best choice.
這樣所產生的符號長度和編譯時間通常都更短，目標文件和調試文件也更小。如果你關注文件的大小和編譯時間，這是你最好的選擇。