Go 的 interface{} 和 C 中的 void* 一样吗？

Question

由于interface{}类型的变量可以具有任何值，这是否意味着它本质上是一个通用指针，如 C 中的 void*？

Answer 1

While C's void * pointers and Go's interface{} variables share the property that you can store arbitrary types, there is one big difference: Go interface variables also store the type of the value they hold.

So while a C programmer is expected to make sure that any casts from void * pointers to specific types are safe, the Go runtime can check that any type assertions are correct.

The type information found in interface variables also allows for sophisticated runtime introspection through the reflect package, which would be impossible with a plain void * pointer.

Answer 2

I am inclined to say "Not at all!". But I admit that it may server the same purpose of "holding whatever comes along".

1. An interface {} is not a pointer so you cannot dereference it.
2. You can cast a void* to anything but type asserting an interface {} might result in a runtime panic.
3. It is complicated (or impossible) to determine the actual type a void* points to but package reflect lets you do this for interface {} .

So no! interface {} is the empty interface and has nothing to do with a void* in C with the small exception that both might be used to handle anything where you do not care about the real nature of it.

Answer 3

No, if the interface type involved is empty—it has no methods—then the itable serves no purpose except to hold the pointer to the original type. In this case, the itable can be dropped and the value can point at the type directly. REF: https://research.swtch.com/interfaces