Golang : Proper way to set function argument default value



Tags : golang function-argument default-values function-parameters

In PHP, it is easy to specify the default values of a function arguments. All you need to do is just specify $argument_variable = default_value in the function arguments such as :

 function word_limiter($str, $limit = 100, $end_char = '…') 
 {
 ...
 }

In Golang, it is not permissible to specify default values in a function arguments using the same method in PHP. Attempt to specify default values for the function arguments will cause the source code parser to throw out syntax error.

This example code below demonstrate the simplest way to set default values in Golang by using the IF statement.

Here you go!

 package main

 import (
 "fmt"
 "strconv"
 )

 func failExample(s string, i int) string {

 // wrong way to set default values
 // will override input parameters/arguments !!!
 s = "empty"
 i = -1

 return s + strconv.Itoa(i)
 }

 func okExample(s string, i int) string {

 // set default values -- the proper way
 if s == "" {
 s = "empty"
 }

 if i == 0 {
 i = -1
 }

 return s + strconv.Itoa(i)
 }

 func main() {

 result := failExample("abc", 123)
 fmt.Println("Fail example : ", result)

 result1 := okExample("abc", 123)
 fmt.Println("Ok example 1 : ", result1)

 result2 := okExample("", 123)
 fmt.Println("Ok example 2 : ", result2)

 result3 := okExample("", 0)
 fmt.Println("Ok example 3 : ", result3)

 }

Output :

Fail example : empty-1

Ok example 1 : abc123

Ok example 2 : empty123

Ok example 3 : empty-1

References:

https://www.socketloop.com/tutorials/golang-return-multiple-values-from-function

https://www.socketloop.com/tutorials/golang-how-to-make-function-callback-or-pass-value-from-function-as-parameter

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  See also : Golang : How to make function callback or pass value from function as parameter?



Tags : golang function-argument default-values function-parameters

By Adam Ng

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