How to Delete Elements from a Slice Stored Within a Go Interface?

Deleting an Element from an Type-Asserted Slice of Interfaces

When manipulating a slice value wrapped within an interface in Go, removing an element directly from the slice is not possible. This operation results in the "cannot assign to value" error because type assertion creates a copy of the value stored in the interface.

Assigning a value to a type-asserted interface does not modify the original value stored in the interface. Instead, it only alters the copy obtained from the type assertion. To circumvent this limitation, consider storing a slice pointer within the interface (*[]interface{}).

Pointer types allow changes to the pointed value rather than the pointer itself. This is demonstrated below:

s := []interface{}{0, "one", "two", 3, 4}

var value interface{} = &s

// Perform removal by accessing the pointed slice
sp := value.(*[]interface{})

i := 2
*sp = append((*sp)[:i], (*sp)[i+1:]...)

fmt.Println(value)

Output:

&[0 one 3 4]

By type-asserting the interface to a slice pointer ([]interface{}) and using the indirection operator (), we can modify the pointed slice value directly.

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