通过其字符串名称将类型转换为特定的结构类型 [英] Typecast to a specific struct type by its string name

问题描述

我想通过使用struct/interface的字符串名称值将特定变量转换为特定的已定义struct/interface.

I would like to typecast a specific variable to a specific defined struct/interface by using the string name value of the struct/interface.

例如:

type Testing interface{}

和新变量

stringName := "Testing"
newTestingVariable.(stringName)

这是偶然的吗?也许使用反射?

Is this possible by chance? Perhaps using reflection?

欢呼

推荐答案

这是不可能的. Go是一种静态类型的语言，这意味着必须在编译时知道变量和表达式的类型.

It is not possible. Go is a statically typed language, which means types of variables and expressions must be known at compile-time.

在类型声明中:

x.(T)

[...]如果类型断言成立，则表达式的值为存储在x中的值，其类型为T.

[...] If the type assertion holds, the value of the expression is the value stored in x and its type is T.

因此，您可以使用类型断言来获取(或测试)您指定的类型的值.

So you use type assertion to get (or test for) a value of a type you specify.

您何时会这样做:

stringName := "Testing"
newTestingVariable.(stringName)

类型断言的结果的类型是什么?你没说您指定了一个包含类型名称的string值，但这只能在 runtime 中确定. (是的，在上面的示例中，编译器可以跟踪作为常量值给出的值，但是在一般情况下，在编译时是不可能的.)

What would be the type of the result of the type assertion? You didn't tell. You specified a string value containing the type name, but this can only be decided at runtime. (Yes, in the above example the compiler could track the value as it is given as a constant value, but in the general case this is not possible at compile time.)

因此，在编译时，编译器只能将interface{}用作类型表达式结果的类型，那又有什么用呢?

So at compile time the compiler could only use interface{} as the type of the result of the type expression, but then what's the point?

如果要动态测试x的类型是否为T(或者如果接口值x实现了T)，则可以对此进行反射(包 reflect ).在这种情况下，您可以使用reflect.Type来指定要测试的类型，而不是其名称的string表示形式.

If the point would be to dynamically test if x's type is T (or that if the interface value x implements T), you can use reflection for that (package reflect). In this case you would use a reflect.Type to specify the type to be tested, instead of a string representation of its name.

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