> For the complete documentation index, see [llms.txt](https://yar999.gitbook.io/gopl-zh/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://yar999.gitbook.io/gopl-zh/ch12.md).

# 反射

Go语音提供了一种机制在运行时更新变量和检查它们的值、调用它们的方法和它们支持的内在操作，但是在编译时并不知道这些变量的具体类型。这种机制被称为反射。反射也可以让我们将类型本身作为第一类的值类型处理。

在本章，我们将探讨Go语言的反射特性，看看它可以给语言增加哪些表达力，以及在两个至关重要的API是如何用反射机制的：一个是fmt包提供的字符串格式功能，另一个是类似encoding/json和encoding/xml提供的针对特定协议的编解码功能。对于我们在4.6节中看到过的text/template和html/template包，它们的实现也是依赖反射技术的。然后，反射是一个复杂的内省技术，不应该随意使用，因此，尽管上面这些包内部都是用反射技术实现的，但是它们自己的API都没有公开反射相关的接口。


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:

```
GET https://yar999.gitbook.io/gopl-zh/ch12.md?ask=<question>&goal=<endgoal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.