How to Correctly Type Assert a Slice of Interface Values in Go?

Type Assertion of Interface Slice Values

When attempting to type assert a slice of interface values, such as []Node, to another type, such as []Symbol, you may encounter the error "invalid type assertion." This error arises because a slice is a distinct, non-interface type. Type checking relies on the notion that a variable's dynamic type remains fixed for interface types, but not for slices or other non-interface types.

Therefore, the statement args.([]Symbol) in the provided code fails because args is of type []Node, which is not an interface type. To type assert properly, you should first convert the slice elements to the desired type, as shown in the following code:

symbols := make([]Symbol, len(args))
for i, arg := range args { symbols[i] = arg.(Symbol) }
fixed, rest := parseFormals(symbols)

This modified code creates an array of Symbol values and iterates over the original []Node slice, type asserting each element to Symbol. After obtaining the desired []Symbol slice, you can perform the necessary operations without encountering type assertion errors.

The above is the detailed content of How to Correctly Type Assert a Slice of Interface Values in Go?. For more information, please follow other related articles on the PHP Chinese website!