问题描述
我注意到一些库，如clojure-twitter使用特殊的vars（用于动态绑定的那些由星号包围）用于oauth身份验证。您将验证保存在var中，然后使用（with-oauth myauth ..）。我认为这是一个很好的解决这类问题，因为你可以重新绑定 auth var应用程序的每个用户。
I've noticed that some libraries such as clojure-twitter use special vars (the ones intended for dynamic binding that are surrounded by asterisks) for oauth authentication. You save your authentication in a var and then use (with-oauth myauth ..). I think this is a very nice solution to this sort of problem, because you can rebind the auth var for each user of the application.
我在我写的电子邮件客户端中采取了类似的路线。我有一个特殊的变量名为 session ，我绑定到一个地图与当前用户的会话和用户信息，有各种重要的函数，使用信息从var。我写了一个宏，使用会话临时重新绑定在一组表单的上下文中传递给会话。原来是一个相当干净的解决方案（对我）。
I've taken a similar route in an email client I've been writing. I have a special var named session that I bind to a map with the current user's session, and user info, and there are various important functions that use information from that var. I wrote a macro, with-session to temporarily rebind it in the context of a set of forms passed to with-session. It turns out to be a pretty clean solution (to me).
所以，我的问题是这样：我'doin'it rite'？这是一个糟糕的设计决定，还是这是特殊变量的预期用途之一？
So, my question is this: am I 'doin' it rite'? Is this a bad design decision, or is this one of the intended usages of special vars?
推荐答案
你似乎在做非常正确。实际上，有一些内置/ contrib宏工作类似， with -out-str 或 clojure.contrib.sql / with -connection 。后者是当今Clojure基础设施中相当重要的一部分，因此它使用的任何习语都经过很多人的审查。
You seem to be doing it exactly right. In fact, there's a number of built-in / contrib macros which work similarly, say with-out-str or clojure.contrib.sql/with-connection. The latter is a rather key part of present day Clojure infrastructure, so whatever idioms it uses have been scrutinised by a lot of people.
要记住的重要的事情是在绑定 / 与绑定范围内启动的线程继承所讨论的var的回弹值;相反，他们看到根绑定。如果你想将你的绑定传播到工作者线程/代理，可以显式地传递它们（作为函数参数），或者使用 bound-fn 。
The important gotcha to keep in mind is that threads you launch while in scope of a bindings / with-bindings form do not inherit the rebound values for the vars in question; rather, they see the root bindings. If you want to propagate your bindings to worker threads / agents, either pass them on explicitly (as function arguments, say) or use bound-fn.
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