[Documentation] Signals need Preserve attribute when used with aggressive code stripping

[robotink]

Fantastic project, thankyou!

Quick note to add to the docs:
When using Signals for mobile and/or using agressive code stripping, Signals will be removed from builds because they aren't statically referenced/linked. You'll want to add a Preserve attribute like this:

using Supyrb;
using UnityEngine.Scripting;

namespace MyNameSpace
{
    [Preserve] //important - must use this attribute if using aggressive stripping on mobile, otherwise this signal won't be found and will throw an error
    public class Signal_MySignal : Signal<bool>
    {
        // Override invoke to make sure that the derived signal class shows up in the stacktrace
        protected override void Invoke(int index)
        {
            base.Invoke(index);
        }
    }
}

[JohannesDeml]

Very good remark, thanks for sharing! I will look into what I can do to handle this. I think it should work with adding a link.xml to the package that handles inherited classes, but I will need to verify this first.

[JohannesDeml]

Hm, dang it. I saw that there is if-inherits-from, but sadly this link.xml does not work for me:

<?xml version="1.0" encoding="utf-8"?>
<linker>
  <!-- Preserve all types that inherit from Supyrb.Signal classes in any assembly -->
  <assembly fullname="*">
    <type fullname="*" preserve="all">
      <if-inherits-from fullname="Supyrb.Signal"/>
      <if-inherits-from fullname="Supyrb.Signal`1"/>
      <if-inherits-from fullname="Supyrb.Signal`2"/>
      <if-inherits-from fullname="Supyrb.Signal`3"/>
    </type>
  </assembly>
</linker>

Sorry, I hoped this would be easy to fix, but apparently this rule is applied to late for it to work. Or there is something else that could be used.

[JohannesDeml]

Alrighty, I found a solution by using [RequireDerived] in the base class for all signals. You can upgrade to https://github.com/supyrb/signals/releases/tag/1.2.0 to get the change in, then you should not need to add a [Preserve] attribute manually anymore - Can you please check that this works for you? :)

[robotink]

hey! Its not such a big deal to add the tags, I was just thinking to add a note to the docs. But with that said, nice job finding the solution. Just did a build on iOS with the update and everything works great!

Thanks again for the package, I've been relying on it for years now. Long ago I built a central directory of Actions<> inspired by the way SteamVR handled hardware events. It worked ok but switching over to Signals smoothed out the bumps and the editor window is super handy for observing and debugging the whole system. Cheers!

[JohannesDeml]

Heya, thanks for confirming that the fix works for you and I'm very glad to read that you find the library useful! Cheers