go-variadic-parameters

what’s variadic parameter in Go

tags: learning go programming

content

• we have this function signature:

func First (query string, replicas ...Search) Result

• ...Search is variadic parameter
• it means the function is expecting any number of replicas
• below function calls are all valid

First("my query")
First("my query", searchEngine1)
First("my query", searchEngine1, searchEngine2)

• inside the First function, replicas behaves like []Search
  • see below replicas[i]

func First(query string, replicas ...Search) Result {
    c := make(chan Result)
    searchReplica := func(i int) { c <- replicas[i](query) }
    for i := range replicas {
		// launching all `Search` replicas in Goroutine
        go searchReplica(i)
    }
    return <-c
}

up

• go

down

reference

• Google I/O 2012 - Go Concurrency Patterns
• Go Concurrency Patterns