Can functions be passed as parameters

Question

In Java I can do something like   derp new Runnable   public void run         run this sometime later           and  run  the code in the method later  It s a pain to handle  anonymous inner class   but it can be done   Does Go have something that can facilitate a function callback being passed in as a parameter

User · Accepted Answer

Yes  consider some of these examples   package main  import  fmt      convert types take an int and return a string value  type convert func int  string     value implements convert  returning x as string  func value x int  string       return fmt Sprintf   v   x        quote123 passes 123 to convert func and returns quoted string  func quote123 fn convert  string       return fmt Sprintf   q   fn 123      func main         var result string      result   value 123      fmt Println result         Output  123      result   quote123 value      fmt Println result         Output   123       result   quote123 func x int  string   return fmt Sprintf   b   x         fmt Println result         Output   1111011       foo    func x int  string   return  foo        result   quote123 foo      fmt Println result         Output   foo           convert foo     confirm foo satisfies convert at runtime         fails due to argument type            convert func x float64  string   return           Play  http   play golang org p XNMtrDUDS0  Tour  https   tour golang org moretypes 25  Function Closures

User · Answer

You can pass function as parameter to a Go function  Here is an example of passing function as parameter to another Go function   package main  import  fmt   type fn func int    func myfn1 i int        fmt Printf   ni is  v   i    func myfn2 i int        fmt Printf   ni is  v   i    func test f fn  val int        f val    func main         test myfn1  123      test myfn2  321      You can try this out at  https   play golang org p 9mAOUWGp0k

User · Answer

Here is the sample  Map  implementation in Go  Hope this helps    func square num int  int       return num   num    func mapper f func int  int  alist   int    int       var a   make   int  len alist   len alist       for index  val    range alist            a index    f val            return a    func main         alist      int 4  5  6  7      result    mapper square  alist      fmt Println result

User · Answer

This is the simplest way I can come with  package main  import  quot fmt quot   func main         g    greeting     getFunc g     func getFunc f func          f      func greeting         fmt Println  quot Hello quot

User · Answer

I hope the below example will provide more clarity   package main  type EmployeeManager struct      category            string     city                string     calculateSalary     func   int64     func NewEmployeeManager     EmployeeManager error        return  amp EmployeeManager          category    MANAGEMENT           city    NY           calculateSalary  func   int64               var calculatedSalary int64                some formula             return calculatedSalary                  nil    func  self  EmployeeManager  emWithSalaryCalculation        self calculateSalary   func   int64           var calculatedSalary int64            some new formula         return calculatedSalary          func updateEmployeeInfo em EmployeeManager          Some code    func processEmployee        updateEmployeeInfo struct           category        string         city            string         calculateSalary func   int64       category      city      calculateSalary  func   int64           var calculatedSalary int64            some new formula         return calculatedSalary

User · Answer

Yes Go does accept first-class functions   See the article  First Class Functions in Go  for useful links

User · Answer

Here is a simple example       package main      import  fmt       func plusTwo    func v int   int             return func v int   int                return v 2                      func plusX x int   func v int   int            return func v int   int               return v x                     func main             p    plusTwo           fmt Printf  3 2   d n   p 3            px    plusX 3          fmt Printf  3 3   d n   px 3

User · Answer

You can also pass the function of a struct  like      package main        define struct     type Apple struct                return apple s color     func  Apple  GetColor   string            return  quot Red quot                  func main                 instantiate         myApple    Apple                       put the func in a variable         theFunc    myApple GetColor                     execute the variable as a function         color    theFunc                print color         output will be  quot Red quot   check on the playground

[function] Can functions be passed as parameters?

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