这段代码在scala中的作用究竟是什么？

Question

我试图理解twitter gizzard示例rowz,我无法弄清楚scala中这个小片段的作用:

package com.twitter.rowz
import com.twitter.gizzard.nameserver.{Forwarding, NameServer}
import com.twitter.gizzard.shards.ShardException

class ForwardingManager(nameServer: NameServer[Shard]) extends (Long => Shard) {  
    def apply(id: Long) = nameServer.findCurrentForwarding(0, id)
}

课程到底是什么？

Answer 1

(A=>B) 是 Function1[A,B]

这些行严格相同:

class ForwardingManager(nameServer: NameServer[Shard]) extends (Long => Shard)
class ForwardingManager(nameServer: NameServer[Shard]) extends Function1[Long,Shard]