Default value in Go s method

Question

Is there a way to specify default value in Go s function  I am trying to find this in the documentation but I can t find anything that specifies that this is even possible   func SaySomething i string    Hello   string

User · Accepted Answer

No  the powers that be at Google chose not to support that   https   groups google com forum   topic golang-nuts -5MCaivW0qQ

User · Answer

NO but there are some other options to implement default value   There are some good blog posts on the subject  but here are some specific examples     Option 1    The caller chooses to use default values    Both parameters are optional  use empty string for default value func Concat1 a string  b int  string     if a     quot  quot        a    quot default-a quot        if b    0       b   5        return fmt Sprintf  quot  s d quot   a  b        Option 2    A single optional parameter at the end    a is required  b is optional     Only the first value in b optional will be used  func Concat2 a string  b optional    int  string     b    5   if len b optional   gt  0       b   b optional 0         return fmt Sprintf  quot  s d quot   a  b        Option 3    A config struct    A declarative default value syntax    Empty values will be replaced with defaults type Parameters struct     A string  default  quot default-a quot      this only works with strings   B string    default is 5    func Concat3 prm Parameters  string     typ    reflect TypeOf prm     if prm A     quot  quot        f       typ FieldByName  quot A quot       prm A   f Tag Get  quot default quot          if prm B    0       prm B   5        return fmt Sprintf  quot  s d quot   prm A  prm B        Option 4    Full variadic argument parsing  javascript style  func Concat4 args    interface    string     a     quot default-a quot    b    5    for    arg    range args       switch t    arg  type          case string          a   t       case int          b   t       default          panic  quot Unknown argument quot                return fmt Sprintf  quot  s d quot   a  b

User · Answer

No  there is no way to specify defaults  I believer this is done on purpose to enhance readability  at the cost of a little more time  and  hopefully  thought  on the writer s end   I think the proper approach to having a  default  is to have a new function which supplies that default to the more generic function  Having this  your code becomes clearer on your intent  For example   func SaySomething say string           All the complicated bits involved in saying something    func SayHello         SaySomething  Hello       With very little effort  I made a function that does a common thing and reused the generic function  You can see this in many libraries  fmt Println for example just adds a newline to what fmt Print would otherwise do  When reading someone s code  however  it is clear what they intend to do by the function they call  With default values  I won t know what is supposed to be happening without also going to the function to reference what the default value actually is

[go] Default value in Go's method

Examples related to go