Generate methods on an existing type

[justenstall]

Describe the solution you'd like

I would like to generate methods on an existing type so the type implements an interface I am defining.

type MyObject struct {
	Name string
	Description string
	Values map[string]string
}

type MyObjectSlim struct {
	Name string
}

// goverter:converter
// goverter:skipCopySameType
// goverter:output:file @cwd/convert.gen.go
// goverter:output:format method *MyObject
type MyObjectConverter interface {
	ConvertToSlim() *MyObjectSlim
}

and have goverter generate the following:

func (source *MyObject) ConvertToSlim() *MyObjectSlim {
   var pMyObjectSlim *MyObjectSlim
   if source != nil {
      var myObjectSlim MyObjectSlim
      myObjectSlim.Name = (*source).Name
   }
   return pMyObjectSlim
}

Describe alternatives you've considered

I can define the methods manually and call the goverter-generated functions from them, but I would prefer to combine those steps to avoid an extra round of code generation.

Please 👍 this issue if you want this functionality. If you have a specific use-case in mind, feel free to comment it.

[jmattheis]

Could you give an example, I don't understand what you mean with extra round of code generation.

[justenstall]

Sure, this is what I would like to do.

I want to write this source:

Example moved to ticket description.

[jmattheis]

Okay. I'm not sure if that's worth the dev effort, as the alternative using functions directly e.g:

var input MyObject = ...

slim := conv.ConvertToSlim(input)

isn't that different as the proposed format

slim := input.ConvertToSlim()

If many users want this feature, I'm cool with changing my mind about this.

---

This project https://github.com/reedom/convergen does support having the source as receiver function, maybe it fits your need.

type Convergen interface {
    // :recv u
    ToStorage(*User) *storage.User  
}

generates:

type User struct {
    ID   int
    Name string
}

func (u *User) ToStorage() (dst *storage.User) {
    dst = &storage.User{}
    dst.ID = int64(u.ID)  
    dst.Name = u.Name

    return
}

https://github.com/reedom/convergen?tab=readme-ov-file#recv-var