C#•10mo ago

Plugin system not casting properly

I'm trying to make a plugin system for my app, which does this:

public void LoadAndRunPlugins()
{
    foreach (string dllFile in Directory.GetFiles(pluginDirectory, "*.dll"))
    {
        try
        {
            Assembly assembly = pluginLoadContext.LoadFromAssemblyPath(Path.GetFullPath(dllFile));

            foreach (Type type in assembly.GetTypes().Where(asm => !asm.FullName.Contains("GyroShell.Library")))
            {
                if (type.GetInterface("IPlugin") != null)
                {
                    IPlugin plugin = Activator.CreateInstance(type) as IPlugin;
                    plugin.Initialize();
                }
            }
        }
        catch (Exception ex)
        {
            Debug.WriteLine($"[-] PluginManager: Error loading and running plugin from {dllFile}: {ex.Message}");
        }
    }
}

public void LoadAndRunPlugins()
{
    foreach (string dllFile in Directory.GetFiles(pluginDirectory, "*.dll"))
    {
        try
        {
            Assembly assembly = pluginLoadContext.LoadFromAssemblyPath(Path.GetFullPath(dllFile));

            foreach (Type type in assembly.GetTypes().Where(asm => !asm.FullName.Contains("GyroShell.Library")))
            {
                if (type.GetInterface("IPlugin") != null)
                {
                    IPlugin plugin = Activator.CreateInstance(type) as IPlugin;
                    plugin.Initialize();
                }
            }
        }
        catch (Exception ex)
        {
            Debug.WriteLine($"[-] PluginManager: Error loading and running plugin from {dllFile}: {ex.Message}");
        }
    }
}

The IPlugin instance is null, so calling plugin.Initialize() throws an NRE. The thing is, it should work just fine, given my plugin code:

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using GyroShell.Library.Interfaces;

namespace TestGyroShellModule
{
    public class PluginRoot : IPlugin
    {
        //public IPluginInfo PluginInformation => new PluginInfo();

        public void Initialize()
        {
            Debug.WriteLine("We're alive from test plugin!");
        }

        public void Shutdown()
        {
            // Shutdown logic
        }

        /*private class PluginInfo : IPluginInfo
        {
            public string Name => "Test GyroShell Plugin";
        }*/
    }
}

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using GyroShell.Library.Interfaces;

namespace TestGyroShellModule
{
    public class PluginRoot : IPlugin
    {
        //public IPluginInfo PluginInformation => new PluginInfo();

        public void Initialize()
        {
            Debug.WriteLine("We're alive from test plugin!");
        }

        public void Shutdown()
        {
            // Shutdown logic
        }

        /*private class PluginInfo : IPluginInfo
        {
            public string Name => "Test GyroShell Plugin";
        }*/
    }
}

And yes, they both reference the same exact interface, defined in GyroShell.Library.Interfaces. Lastly, I've tried debugging this and nothing should go wrong. It tries to cast the PluginRoot class to an IPlugin, which should work since it properly implements the interface, but it just fails. No exceptions are thrown.

40 Replies

br4kejet•10mo ago

I'd do if (typeof(IPlugin).IsAssignableFrom(type))

PdawgOP•10mo ago

Okay, I'll try this There's not an NRE anymore, but now it just fails to cast. Once again, no exceptions are thrown, and it should work just fine The test plugin references GyroShell.Library, so it's definitely implementing the correct interface

Jimmacle•10mo ago

if you expect the cast to succeed, use a C style cast instead of as so you get an invalid cast exception if something unexpected happens

PdawgOP•10mo ago

Okay Well

Jimmacle•10mo ago

that will give you more info than it just returning null

PdawgOP•10mo ago

if (typeof(IPlugin).IsAssignableFrom(type)) it never gets past here though This is before the cast can be done

Jimmacle•10mo ago

then the cast isn't failing

PdawgOP•10mo ago

It thinks that you can't cast PluginRoot even though it implements the interface properly

br4kejet•10mo ago

Are you sure it's even processing your plugin's dll?

PdawgOP•10mo ago

I believe so, when I tried debugging, the module showed up along with its respective Types

br4kejet•10mo ago

Set a breakpoint on the LoadFromAssemblyPath line, and set a breakpoint on the typeof(IPlugin).IsAssignable... line with a condition of type.Name == "PluginRoot" And then check the debugger local variables for the type and see if it's correct

PdawgOP•10mo ago

Okay. Also, I tried the C Style cast and got a generic exception out of it:

br4kejet•10mo ago

Maybe there's a version difference since you compiled the PluginRoot and the CLR doesn't like it

Jimmacle•10mo ago

do you have multiple types called IPlugin?

PdawgOP•10mo ago

nope, just one trying this rn

PdawgOP•10mo ago

@br4kejet

PdawgOP•10mo ago

This next breakpoint is never hit

br4kejet•10mo ago

If you move next then it should try to run CreateInstance or you could do that

PdawgOP•10mo ago

It just fails at the if statement, it thinks that the PluginRoot isn't assignable to IPlugin It won't run the CreateInstance

br4kejet•10mo ago

Click the little arrow thing on type

Jimmacle•10mo ago

are you absolutely 100% sure there aren't multiple types in your project called IPlugin?

br4kejet•10mo ago

Explore the interfaces

Jimmacle•10mo ago

because what this is indicating is the IPlugin you're testing against and the IPlugin the type implements are different types

PdawgOP•10mo ago

I'm certain that they're implementing the same interface

PdawgOP•10mo ago

PluginRoot implements GyroShell.Library.Interfaces.IPlugin

br4kejet•10mo ago

I dunno then, the code I gave worked for me Though I use an abstract class instead of an interface

PdawgOP•10mo ago

should I do that instead?

br4kejet•10mo ago

Could try it

PdawgOP•10mo ago

It doesn’t really matter which method I use, as long as it’s not some crude manual reflection thing

br4kejet•10mo ago

Then if that works try using an interface again

PdawgOP•10mo ago

I’ll try an abstract later, I gotta go eat dinner Thanks for the help though

Jimmacle•10mo ago

dunno if it'll help but here's relevant code from the last plugin loader i was involved with https://github.com/TorchAPI/Torch/blob/master/Torch/Plugins/PluginManager.cs#L506-L573

PdawgOP•10mo ago

Cool, I’ll look into it later. Thanks! @br4kejet Hey, I'm back, and I tried an abstract class same problem as before I'll check the version of .NET and WASDK Nope, they're on the same version of WASDK and .NET oh wait what i just fixed it for some reason, when the assembly loader attemped to load the file, it was also loading the reference library. i thought that was the issue earlier, but i fixed it at the wrong spot. the issue needs to be fixed before the file even loads

PdawgOP•10mo ago

it's working now weird behavior nonetheless but hey it works 🤷

PdawgOP•10mo ago

there we go

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Plugin system not casting properly