这段代码在 scala 中到底做了什么？
我试图理解 twitter gizzard 示例 rowz，但我无法弄清楚这个小片段在 scala 中的作用：
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)
}
类到底扩展了什么？
I'm trying to understand the twitter gizzard example rowz, and I can't figure out what this little snippet does in scala:
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)
}
what exactly is the class extending?
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(A=>B)是Function1[A,B]这些行是严格等效的：
(A=>B)isFunction1[A,B]Those lines are strictly equivalent:
此代码段定义了扩展
Function1[Long, Shard]的类ForwardingManager（Long => Shard只是缩写形式）。作为另一个示例，您可以查看 Scala 库中的
Parser类：https://github.com/scala/scala/blob/master/src/library/scala/util/parsing/combinator/Parsers.scala#L190< /a>
在这种情况下
(Input => ParseResult[T])与Function1[Input, ParseResult[T]]相同。 Programming in Scala, 2nd Edition（第 33.6 节）中也描述了这个具体示例This snippet defines class
ForwardingManagerthat extendsFunction1[Long, Shard](Long => Shardis just short form).As another example, you can look at
Parserclass from Scala library:https://github.com/scala/scala/blob/master/src/library/scala/util/parsing/combinator/Parsers.scala#L190
In ths case
(Input => ParseResult[T])is the same asFunction1[Input, ParseResult[T]]. This concrete example is described also in Programming in Scala, 2nd Edition (section 33.6)