rustdestructuring

Is this the idiomatic way to get the wanted variant out of an enum without causing nesting?

I have this working code:

/* Ignore IPv6. */
let via = if let IpAddr::V4(via) = addr.ip() {
    via
} else {
    warn!("(unsupported) ipv6 packet from ${addr}");
    continue // abandon this packet and try the next packet
};

// ...process this packet with "via: Ipv4Addr" in scope...

Is there an idiomatic way to get the wanted variant out of an enum, without via being mentioned three times?

Or is this how I should ignore unwanted variants in Rust?

Solution

  • You can use let-else, since the else branch is diverging (continue):

    /* Ignore IPv6. */
let IpAddr::V4(via) = addr.ip() else {
    warn!("(unsupported) ipv6 packet from ${addr}");
    continue // abandon this packet and try the next packet
};

// ...process this packet with "via: Ipv4Addr" in scope...