Why Does `reflect.ValueOf(&value).Elem()` Trigger a Panic When Using `FieldByName` on a Pointer?

Addressing Panic in Reflect.Value.FieldByName

The .FieldByName method of a reflected value can trigger a panic if the value is a pointer. To resolve this, it's crucial to understand the structure and type of the value.

Consider the provided code:

s := reflect.ValueOf(&&value).Elem()
metric := s.FieldByName(subval.Metric).Interface()

In this code, the value is a struct, and the ValueOf() function is used to obtain a reflected value of &value, which is a pointer to the struct. However, calling Elem() on this reflected value effectively dereferences the pointer.

Therefore, a correct approach would be to directly obtain a reflected value of value:

s := reflect.ValueOf(value).Elem()
metric := s.FieldByName(subval.Metric).Interface()

By skipping the unnecessary indirection, this code avoids creating an unnecessary pointer, leading to a successful execution without the panic.

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