How Can I Perform Type Assertion in Go When the Concrete Type Is Unknown?

Type Assertion in Golang for Unknown Interface

In Golang, type assertion allows you to convert an interface to a concrete type. However, what if the concrete type is unknown? This article delves into the limitations and a deeper understanding of type assertion in such scenarios.

Traditionally, type assertion is performed using the form:

out := reflect.ValueOf(obj).Elem().Interface().(User)

where you specify the concrete type, such as User in this case. This works for known types, but not for unknown types.

Within a function like:

func Foo(obj interface{}) bool {
    // ...
}

you encounter the challenge of type assertion without knowing the concrete type.

The problem arises because type assertions rely on static type checking. The compiler needs to know the concrete type to generate the appropriate check at runtime.

During type assertion, the compiler checks if the interface value has the same type as the specified concrete type. If not, it panics with an error. The runtime check ensures that only compatible types are converted, maintaining type safety.

Therefore, it is not possible to perform type assertion on an unknown interface in Golang. The compiler requires the concrete type to perform the necessary checks and guarantee type safety.

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