可以静态组合用作 thread_local 的占位符？
C++0x 添加了新的存储说明符 thread_local VS10 中尚未实现。
但是，并行编程库定义了 Concurrency::combinable class 具有一个 local() 函数，该函数返回对线程私有子计算的引用。
是否有 thread_local 的语义无法（轻松）通过使用 combinable 类型的 static 变量来覆盖？
如果不是的话，如果可以在库中实现，为什么还要将 thread_local 添加到核心语言中？
C++0x adds a new storage specifier thread_local which is not yet implemented in VS10.
However the Parallel Programming Library defines a Concurrency::combinable class which has a local() function which Returns a reference to the thread-private sub-computation.
Are there semantics for thread_local that can't be (easily) covered by having a static variable of type combinable<T>?
If not why was thread_local added to the core language if it can be implemented in a library?
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为什么 C++ 添加了 class 对象，是否可以像 C 中的 GObject 那样由库实现？因为 C++ 希望在编译时知道类对象，所以这样效率更高。因此，C++ 类初始化/取消初始化是异常安全的 (RAII)。
有些功能比较重要，需要更多的实施。 thread_local是一个存储类说明符，因此可以在编译时知道它，编译器可以做更多的优化。
也在 http://www.open- std.org/jtc1/sc22/wg21/docs/papers/2008/n2659.htm 说过：
为什么
thread_local被引入作为新的语言关键字？看来原因可能是线程变量动态初始化。Why C++ added class objects whether it could be implemented by a library like something that GObject does in C? Because C++ wants class objects to be known at compile-time, this is more efficient. Therefore C++ class initialization/uninitialization is exception-safe (RAII).
Some features are more major and needed more implementation to be made. thread_local is a storage class specifier, so it can be known at compile-time and compiler can do much more optimization.
Also in http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/n2659.htm have said:
Why
thread_localhave been introduced as a new language keyword? It seems that the reason could be Thread Variable Dynamic Initialization.