Could you expand on reverse bindings?

[willauld]

In the summary of your talk you mention using reverse bindings, I have been attempting this (calling back into java from go) but I can't seem to get the formula right. David Crawshaw in a discussion thread (https://groups.google.com/forum/#!topic/Golang-Nuts/DRpXR6P-eG8) explains how to do it but I can't get it to work.

Would you highlight where this is done in your example code?

Thanks,
Will

 Summary

- Use Go Mobile to share non-trivial Go across mobile platforms Android/iOS.
- Use the reverse bindings with care; they're still experimental.
- Look out for reference cycles, when references cross the language barriers.

[eliasnaur]

What did you try and what went wrong? There is example code in this repository (src/goaccount), but the example from gomobile (https://github.com/golang/mobile/tree/master/example/reverse) should work as well.

[willauld]

I put together a small github repo that shows the problem I am not able to get past. The repo has a trivial android app with two buttons. This first is to call go from java and show the passing of a string back and forth. The second (which is not building) is to call go and in turn call back into java. The repo is: https://github.com/willauld/goMobileBindExample I am trying to follow the method explained by David Crawshaw (ref below) and a very similar blog post by Mat Ryer (ref below). I looked at the reverse example you referenced but I don’t understand it. It says its 100% go and I am trying to call back and forth… Thanks, Will /* Two main examples on how the callback into java should be done. First: https://medium.com/@matryer/tutorial-calling-go-code-from-swift-on-ios-and-vice-versa-with-gomobile-7925620c17a4 Second Example explanation given in https://groups.google.com/forum/#!topic/Golang-Nuts/DRpXR6P-eG8 "That said, I think your project is very interesting and I hope you keep working on it. One thing I noticed on a quick look through your code: you may not realize that gobind will manage callbacks from Java into Go. That is if your Go package defines: " type Callback interface { CallJava(x T) U } func Register(c Callback) { c.CallJava(x) // c can be stored for later use } Then in Java you can subclass the generated class and implement the CallJava method: public class J extends gopkg.Callback { public CallJava(T x) U { // code you want called from Go. } } ... gopkg.Register(new J()); */ From: Elias Naur [mailto:notifications@github.com] Sent: Tuesday, December 19, 2017 1:33 AM To: eliasnaur/golab-2017-talk <golab-2017-talk@noreply.github.com> Cc: Will Auld <will@auld.com>; Author <author@noreply.github.com> Subject: Re: [eliasnaur/golab-2017-talk] Could you expand on reverse bindings? (#1) What did you try and what went wrong? There is example code in this repository (src/goaccount), but the example from gomobile (https://github.com/golang/mobile/tree/master/example/reverse) should work as well. — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#1 (comment)> , or mute the thread <https://github.com/notifications/unsubscribe-auth/AJhyORdnwFqctvlEuyqbMkCkxw1BDCCpks5tB4LQgaJpZM4RGS0k> .

[willauld]

I think I've got it working now. Just put the latest changes up to the github repo. Will do more testing to make sure but I think I have it.

Thanks,
Will