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x/mobile/bind: support slices of supported structs
Just want to know if it will ever be possible to support slices of supported. I currently have to write a wrapper object around an array to pass it back and forth between IOS and Go.
It will not be impossible and eventually it should be supported. I don't know anyone who's currently working on this problem.
Do you have any ideas when this will be done? What I could do?
I tried and failed using: https://golang.org/pkg/container/list/ as an alternative
This is stopping me from using gomobile in anything worthwhile at the moment
@scisci - If you don't mind can you please share across a gist on how you handle the problem currently as said? My requirement would be to return an array/slice of custom modal class objects with 4 string properties.
hi @ioArchman, I made a quick repo here:
https://github.com/scisci/go-mobile-collection
If you think it can work for you, you will probably want to fork it and modify the render.go function to add/remove the methods you want on your collection wrapper. Feel free to make a comment on the project if you have any questions. Its pretty directly adapted from another tutorial on go generics, which you can find here http://www.onebigfluke.com/2014/12/generic-programming-go-generate.html
Keep in mind, I don't consider this a good solution. It feels hacky working with a wrapper on the objective-c/swift side, but it does work. Really would prefer something that feels more natural.
Thanks @scisci. Will look into this and try utilizing for now. Agreed on your last point too.
hi @hyangah, do you have any hints on how this would be technically implemented in case someone wanted to attempt it from outside the gomobile team?
Is this still on the road map? I found this library and would like to use it, but this issue may be keep me from using gomobile.
It seems this is a show-stopper for many people. Are there any plans to support this?
What's the status of this issue? It has been around for quite a while. It looks like the main show stopper for many people.
CC: @hyangah @crawshaw
Just linking the stack overflow question here : https://stackoverflow.com/questions/44382115/golang-gomobile-tool-for-cross-platform-slices-of-struct-return-type
Currently no one is working on the x/mobile project and adding this feature is not a small project.
Not ideal but need to work around by writing a wrapper package for binding, or using what @scisci mentioned for now.
It's community supported at this point, so its future depends on you. There are others from the community working on it, but not full time.
Anyone currently working on this? If not, could you give some pointers where to start with this?
As a really slow and dumb bypass, you could serialize the data into JSON, pass the string and unserialize it on the other side. Use this only as a last resort, though.
A workaround from my real project. Maybe will helpful for someone. On Go side:
type Field struct {
Key string
Value string
Protected bool
}
type FieldReceiver interface {
Add(field *Field)
}
func GetEntryFields(receiver FieldReceiver) {
for _, v := range entry.Values {
field := Field{
Key: v.Key,
Value: v.Value.Content,
Protected: v.Value.Protected}
receiver.Add(&field)
}
}
Android side:
val fields = mutableListOf<Field>()
Mylib.getEntryFields() { field ->
run {
fields += Field(field.key, field.value, field.protected)
}
}
A workaround with String as an example:
type StringCollection interface {
Add(s string) StringCollection
Get(i int) string
Size() int
}
// TODO solve this with generics
type StringArray struct {
items []string
}
func (array StringArray) Add(s string) StringArray {
array.items = append(array.items, s)
return array
}
func (array StringArray) Get(i int) string {
return array.items[i]
}
func (array StringArray) Size() int {
return len(array.items)
}
Usage in go:
func GetExampleStringArray() *StringArray {
strings := []string{"example1", "example2"}
return &StringArray{items: strings}
}
On Android you can use this extension to convert it to a List<String>:
fun StringArray.toStringList(): List<String> {
val list = mutableListOf<String>()
for (i in 0 until size()) {
list.add(get(i))
}
return list
}
fun main() {
GoPackage.getExampleStringArray().toStringList()
}
Is there any news? I was very surprised that this isn't implemented by default, I need to make very ugly workarounds to make my binding work.
I've implemented most of the work required for slices of structs here: https://github.com/golang/mobile/pull/101
I could certainly use some help on the final stretch though, especially if you've managed to get the gobind test environment working correctly. In particular, I think the last bits necessary are to:
- Update the go-side refnum marshalling
- Add an Obj-C implementation
- Test that it all works
Change https://go.dev/cl/583196 mentions this issue: bind: support slices of structs
