C++ 什么是匿名对象？
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What is an Anonymous Object?
提问by Sadique
What is an Anonymous Object exactly?
什么是匿名对象？
Does C++ support/have Anonymous Objects?
C++ 是否支持/具有匿名对象？
回答by Lightness Races in Orbit
The C++ standard does not define the term "anonymous object", but it stands to reason that one might sanely use the term to describe any object that has no name:
C++ 标准没有定义术语“匿名对象”，但可以合理地使用该术语来描述任何没有名称的对象：
- Temporaries:
f(T()); - Unnamed function parameters:
void func(int, int, int);
- 临时工：
f(T()); - 未命名的函数参数：
void func(int, int, int);
What I wouldn'tcount is dynamically-allocated objects:
我不会计算的是动态分配的对象：
Technically speaking, an "object" is any region of storage [1.8/1 in 2003], which would include the X bytes making up the integer dynamically-allocated by new int;.
从技术上讲，“对象”是存储的任何区域 [2003 年的 1.8/1]，其中包括由new int;.
In int* ptr = new int;the pointer (itself an object too, don't forget!) has the name ptrand the integer itself has no name other than *ptr. Still, I'd hesitate to call this an anonymous object.
在int* ptr = new int;指针中（它本身也是一个对象，不要忘记！）具有名称ptr，而整数本身除了*ptr. 尽管如此，我还是会犹豫将其称为匿名对象。
Again, though, there's no standard terminology.
不过，同样没有标准术语。
回答by Bob Fincheimer
This is a simplistic answer, but an anonymous object is basically an object which the compiler creates a classfor.
这是一个简单的答案，但匿名对象基本上是编译器class为其创建的对象。
For example in C# (I know this is kinda irrelevant) you can just create an anonymous type by doing:
例如在 C# 中（我知道这有点无关紧要），您可以通过执行以下操作来创建匿名类型：
new { filename = value }.
new { filename = value }.
The compiler effectively creates a class called AnonSomething1[A random name you don't know] which has those fields. Therefore at that point you just created an instance of that AnonSomething1. C++ does not allow you to make anonymous class types inline (like Java and C# which have a base Object class which the anon types can derive).
编译器有效地创建了一个名为AnonSomething1[您不知道的随机名称] 的类，其中包含这些字段。因此，那时您刚刚创建了 that 的一个实例AnonSomething1。C++ 不允许您内联匿名类类型（如 Java 和 C#，它们具有匿名类型可以派生的基本 Object 类）。
However you can make an anonymous struct by simply writing
但是，您可以通过简单地编写匿名结构
struct {
int field1;
std::string field2;
} myanonstruct;
which creates an anonymous struct and instantiates it with the alias myanonstruct. This C++ code does not define a type, it just creates an anonymous one with 1 instance.
它创建一个匿名结构并使用别名实例化它myanonstruct。这段 C++ 代码没有定义类型，它只是创建了一个具有 1 个实例的匿名类型。
See C#: Anon Types
请参阅 C#：匿名类型
See Java: Anon Types
请参阅 Java：匿名类型
See C++ Structs: msdn
请参阅 C++ 结构：msdn
