📅 最后修改于: 2020-11-05 04:06:09 🧑 作者: Mango
正如多次指出的那样，Clojure是一种编程语言，其中许多数据类型是不可变的，这意味着更改变量值的唯一方法是创建一个新变量并为其分配新值。但是，Clojure确实提供了一些可以创建可变状态的元素。我们已经看到，这可以通过原子数据类型来实现。可以通过代理实现的另一种方式。
代理为各个位置提供独立的异步更改。代理在其整个生命周期内都绑定到一个存储位置，并且仅允许该位置由于操作而发生突变(变为新状态)。动作是函数(具有可选的其他参数)，这些函数被异步应用于代理的状态，并且其返回值成为代理的新状态。
关于代理，在Clojure中可以进行以下操作。
| Sr.No. | Operations & Description |
|---|---|
| 1 | agent
An agent is created by using the agent command. |
| 2 | send
This function is used to send across a value to the agent. |
| 3 | shutdown-agents
This function is used to shut down any running agents. |
| 4 | send-off
There are instances wherein an agent is assigned a function which is blocking in nature. |
| 5 | await-for
Since there is a delay when a value of an agent is updated, Clojure provided a ‘await-for’ function which is used to specify time in milliseconds to wait for the agent to be updated. |
| 6 | await
Blocks the current thread (indefinitely!) until all actions dispatched thus far, from this thread or agent, to the agent(s) have occurred. Will block on failed agents. |
| 7 | agent-error
Returns the exception thrown during an asynchronous action of the agent, if the agent fails. Returns nil if the agent does not fail. |