nathanAjacobs Posts - Answer Overflow

nathanAjacobs

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•Created by nathanAjacobs on 3/3/2025 in #help

Managed callback to native code (reverse p/invoke)

If I pass a managed callback to native code, do I need to pin the stored delegate so it does not get moved to a new memory address or is this handled by the runtime?

public class MyTestClass
{
    private delegate void NativeTestCallback(int num);

    [DllImport("TestNative")]
    private static extern void NativeFunc(NativeTestCallback callback);

    private NativeTestCallback _callback;
    public MyTestClass()
    {
        // do I need to pin this?
        _callback = TestCallback;
        NativeFunc(_callback);
    }

    private void TestCallback(int num)
    {

    }
}

public class MyTestClass
{
    private delegate void NativeTestCallback(int num);

    [DllImport("TestNative")]
    private static extern void NativeFunc(NativeTestCallback callback);

    private NativeTestCallback _callback;
    public MyTestClass()
    {
        // do I need to pin this?
        _callback = TestCallback;
        NativeFunc(_callback);
    }

    private void TestCallback(int num)
    {

    }
}

6 replies

CC#

•Created by nathanAjacobs on 2/21/2025 in #help

Would this AsyncQueue have issues with multiple producers and a single consumer?

First, I know Channels exist and I would obviously use them instead. I can't use them because I'm adding functionality to an existing Unity library that does not have access to them. I'm intending to use this internally in the library for IPC purposes between Unity Editor instances. Will this implementation have issues with synchronization? Also will FIFO be preserved? I think the answer is there are no issues with this, but want to confirm.

internal class AsyncQueue<T>
{
    private readonly ConcurrentQueue<T> _queue = new ConcurrentQueue<T>();
    private readonly SemaphoreSlim _semaphore = new SemaphoreSlim(0);

    public void Enqueue(T item)
    {
        _queue.Enqueue(item);
        _semaphore.Release();
    }

    public async Task<T> DequeueAsync()
    {
        await _semaphore.WaitAsync().ConfigureAwait(false);
        if (_queue.TryDequeue(out T item))
        {
            return item;
        }

        throw new InvalidOperationException("Something went wrong, there is nothing to dequeue.");
    }
}

internal class AsyncQueue<T>
{
    private readonly ConcurrentQueue<T> _queue = new ConcurrentQueue<T>();
    private readonly SemaphoreSlim _semaphore = new SemaphoreSlim(0);

    public void Enqueue(T item)
    {
        _queue.Enqueue(item);
        _semaphore.Release();
    }

    public async Task<T> DequeueAsync()
    {
        await _semaphore.WaitAsync().ConfigureAwait(false);
        if (_queue.TryDequeue(out T item))
        {
            return item;
        }

        throw new InvalidOperationException("Something went wrong, there is nothing to dequeue.");
    }
}

18 replies

CC#

•Created by nathanAjacobs on 2/10/2025 in #help

How can I reference multiple generics in summary?

This does not work. Is there a way to do this?

/// <summary>
/// </summary>
/// <returns>
/// A <see cref="Task{Handle{T}}"/>
/// </returns>
public async Task<Handle<T>> Foo()
{
}

/// <summary>
/// </summary>
/// <returns>
/// A <see cref="Task{Handle{T}}"/>
/// </returns>
public async Task<Handle<T>> Foo()
{
}

14 replies

CC#

•Created by nathanAjacobs on 2/1/2025 in #help

Reccomended approach for sending messages from ASP.NET backend server to TypeScript web front-end?

10 replies

CC#

•Created by nathanAjacobs on 1/27/2025 in #help

Prevent Visual Studio from adding NotImplementedException when generating method

Is it possible to configure Visual Studio to not add the throw new NotImplementedException(); line when generating methods via quick actions? I just want it to create an empty method.

13 replies

CC#

•Created by nathanAjacobs on 1/8/2025 in #help

Declaring methods with `in` parameters

If a I'm writing a synchronous method, should I always declare read-only value types with the in keyword.

void Foo(in int i)
{
    
}

void Foo(in int i)
{
    
}

17 replies

AAE📼 Addie’s Analog Emporium 🌐

•Created by nathanAjacobs on 12/24/2024 in #tech-help

Adobe Audition not saving "Monitor Input" for saved multitrack session

Every time I open my saved session, I have to enable the I monitor input button Does anyone know why this might be the case?

1 replies

CC#

•Created by nathanAjacobs on 12/2/2024 in #help

WPF - Custom Control Help

See attached files, the template binding to FlyoutDirection is not working. I am getting this exception:

System.Windows.Markup.XamlParseException
  HResult=0x80131501
  Message='Set property 'System.Windows.Condition.Binding' threw an exception.' Line number '46' and line position '34'.
  Source=<Cannot evaluate the exception source>
  StackTrace:
<Cannot evaluate the exception stack trace>

  This exception was originally thrown at this call stack:
    [External Code]

Inner Exception 1:
InvalidCastException: Unable to cast object of type 'System.Windows.TemplateBindingExpression' to type 'System.Windows.Data.BindingBase'.

System.Windows.Markup.XamlParseException
  HResult=0x80131501
  Message='Set property 'System.Windows.Condition.Binding' threw an exception.' Line number '46' and line position '34'.
  Source=<Cannot evaluate the exception source>
  StackTrace:
<Cannot evaluate the exception stack trace>

  This exception was originally thrown at this call stack:
    [External Code]

Inner Exception 1:
InvalidCastException: Unable to cast object of type 'System.Windows.TemplateBindingExpression' to type 'System.Windows.Data.BindingBase'.

3 replies

CC#

•Created by nathanAjacobs on 11/27/2024 in #help

CommunityToolkit.MVVM ObservableProperty and JsonIgnore

I have an observable property like so:

[ObservableProperty]
private string _online;

[ObservableProperty]
private string _online;

Is there any way to specify that the generated property be ignored for json serialization?

7 replies

CC#

•Created by nathanAjacobs on 11/26/2024 in #help

WPF - DataGridCheckBoxColumn Issues

In WPF, how can I have a DataGridCheckBoxColumn that allows me to click the checkboxes without having to select the row first. It's weird that when I click the checkbox it selects the row rather than just clicking the checkbox I have this which seems to work, but it doesn't seem to update the value in the model when the checkbox is clicked. It only gets updated when I click the cell and click away. How can I fix it so that when I click the checkbox it updates the model?

<DataGridTemplateColumn Header="Enabled" MinWidth="100" Width="100">
    <DataGridTemplateColumn.CellTemplate>
        <DataTemplate>
            <CheckBox IsChecked="{Binding Enabled, Mode=TwoWay}" VerticalAlignment="Center" HorizontalAlignment="Center"/>
        </DataTemplate>
    </DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>

<DataGridTemplateColumn Header="Enabled" MinWidth="100" Width="100">
    <DataGridTemplateColumn.CellTemplate>
        <DataTemplate>
            <CheckBox IsChecked="{Binding Enabled, Mode=TwoWay}" VerticalAlignment="Center" HorizontalAlignment="Center"/>
        </DataTemplate>
    </DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>

5 replies

CC#

•Created by nathanAjacobs on 11/4/2024 in #help

Deep copying data from class instances

Is there something that can generically and efficiently deep copy all of the data from one instance of a class into another already existing instance?

14 replies

CC#

•Created by nathanAjacobs on 10/23/2024 in #help

Aspire and PgAdmin

3 replies

CC#

•Created by nathanAjacobs on 10/7/2024 in #help

✅ Can you run EF Core migration update at application startup rather than with the CLI tools?

8 replies

CC#

•Created by nathanAjacobs on 10/6/2024 in #help

Is it necessary to setup validation constraints at the api level and database level?

I'm setting up a minimal api and just started to use FluentValidation. Should I also setup validation constraints at the database level as well?

6 replies

CC#

•Created by nathanAjacobs on 9/2/2024 in #help

Worse performance with pointers?

9 replies

CC#

•Created by nathanAjacobs on 6/5/2024 in #help

NamedPipeClientStream.ReadAsync() continuously reads after the first message arrives

How come NamedPipeClientStream.ReadAsync continuously reads 0 bytes after the first message arrives? Basically is there a way to have it asynchronously wait until more data arrives after the first message?

5 replies

CC#

•Created by nathanAjacobs on 5/6/2024 in #help

Can Memory<T> be created from a pointer?

Can Memory<T> be created with a pointer and a length? If not, how come?

15 replies

CC#

•Created by nathanAjacobs on 2/27/2024 in #help

Help with LibraryImport and custom marshalling

What am I doing wrong here? I am getting a System.AccessViolationException when it tries to convert the first string (DeviceName) from unmanaged to managed.

[LibraryImport("user32.dll", EntryPoint = "EnumDisplayDevicesW", StringMarshalling = StringMarshalling.Utf16)]
[return: MarshalAs(UnmanagedType.Bool)]
public static partial bool EnumDisplayDevices(string? lpDevice, uint iDevNum, [MarshalUsing(typeof(DISPLAY_DEVICEMarshaller))] ref DISPLAY_DEVICE lpDisplayDevice, uint dwFlags);

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
public struct DISPLAY_DEVICE
{
    [MarshalAs(UnmanagedType.U4)]
    public uint cb;
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 32)]
    public string? DeviceName;
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 128)]
    public string? DeviceString;
    [MarshalAs(UnmanagedType.U4)]
    public DisplayDeviceStateFlags StateFlags;
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 128)]
    public string? DeviceID;
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 128)]
    public string? DeviceKey;

    public static DISPLAY_DEVICE Create() => new DISPLAY_DEVICE { cb = (uint)Marshal.SizeOf<DISPLAY_DEVICE>() };
}

[Flags]
public enum DisplayDeviceStateFlags : uint
{
    AttachedToDesktop = 0x1,
    MultiDriver = 0x2,
    PrimaryDevice = 0x4,
    MirroringDriver = 0x8,
    VGACompatible = 0x10,
    Removable = 0x20,
    ModesPruned = 0x8000000,
    Remote = 0x4000000,
    Disconnect = 0x2000000
}

[CustomMarshaller(typeof(DISPLAY_DEVICE), MarshalMode.ManagedToUnmanagedRef, typeof(DISPLAY_DEVICEMarshaller))]
public static unsafe class DISPLAY_DEVICEMarshaller
{
    internal struct DISPLAY_DEVICE_Unmanaged
    {
        public uint cb;
        public ushort* DeviceName;
        public ushort* DeviceString;
        public uint StateFlags;
        public ushort* DeviceID;
        public ushort* DeviceKey;
    }

    public static DISPLAY_DEVICE ConvertToManaged(DISPLAY_DEVICE_Unmanaged unmanaged)
    {
        return new DISPLAY_DEVICE
        {
            cb = unmanaged.cb,
            DeviceName = Utf16StringMarshaller.ConvertToManaged(unmanaged.DeviceName),
            DeviceString = Utf16StringMarshaller.ConvertToManaged(unmanaged.DeviceString),
            StateFlags = (DisplayDeviceStateFlags)unmanaged.StateFlags,
            DeviceID = Utf16StringMarshaller.ConvertToManaged(unmanaged.DeviceID),
            DeviceKey = Utf16StringMarshaller.ConvertToManaged(unmanaged.DeviceKey)
        };
    }

    public static DISPLAY_DEVICE_Unmanaged ConvertToUnmanaged(DISPLAY_DEVICE managed)
    {
        return new DISPLAY_DEVICE_Unmanaged
        {
            cb = managed.cb,
            DeviceName = Utf16StringMarshaller.ConvertToUnmanaged(managed.DeviceName),
            DeviceString = Utf16StringMarshaller.ConvertToUnmanaged(managed.DeviceString),
            StateFlags = (uint)managed.StateFlags,
            DeviceID = Utf16StringMarshaller.ConvertToUnmanaged(managed.DeviceID),
            DeviceKey = Utf16StringMarshaller.ConvertToUnmanaged(managed.DeviceKey)
        };
    }

    public static unsafe void Free(DISPLAY_DEVICE_Unmanaged unmanaged)
    {
        Utf16StringMarshaller.Free(unmanaged.DeviceName);
        Utf16StringMarshaller.Free(unmanaged.DeviceString);
        Utf16StringMarshaller.Free(unmanaged.DeviceID);
        Utf16StringMarshaller.Free(unmanaged.DeviceKey);
    }
}

[LibraryImport("user32.dll", EntryPoint = "EnumDisplayDevicesW", StringMarshalling = StringMarshalling.Utf16)]
[return: MarshalAs(UnmanagedType.Bool)]
public static partial bool EnumDisplayDevices(string? lpDevice, uint iDevNum, [MarshalUsing(typeof(DISPLAY_DEVICEMarshaller))] ref DISPLAY_DEVICE lpDisplayDevice, uint dwFlags);

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
public struct DISPLAY_DEVICE
{
    [MarshalAs(UnmanagedType.U4)]
    public uint cb;
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 32)]
    public string? DeviceName;
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 128)]
    public string? DeviceString;
    [MarshalAs(UnmanagedType.U4)]
    public DisplayDeviceStateFlags StateFlags;
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 128)]
    public string? DeviceID;
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 128)]
    public string? DeviceKey;

    public static DISPLAY_DEVICE Create() => new DISPLAY_DEVICE { cb = (uint)Marshal.SizeOf<DISPLAY_DEVICE>() };
}

[Flags]
public enum DisplayDeviceStateFlags : uint
{
    AttachedToDesktop = 0x1,
    MultiDriver = 0x2,
    PrimaryDevice = 0x4,
    MirroringDriver = 0x8,
    VGACompatible = 0x10,
    Removable = 0x20,
    ModesPruned = 0x8000000,
    Remote = 0x4000000,
    Disconnect = 0x2000000
}

[CustomMarshaller(typeof(DISPLAY_DEVICE), MarshalMode.ManagedToUnmanagedRef, typeof(DISPLAY_DEVICEMarshaller))]
public static unsafe class DISPLAY_DEVICEMarshaller
{
    internal struct DISPLAY_DEVICE_Unmanaged
    {
        public uint cb;
        public ushort* DeviceName;
        public ushort* DeviceString;
        public uint StateFlags;
        public ushort* DeviceID;
        public ushort* DeviceKey;
    }

    public static DISPLAY_DEVICE ConvertToManaged(DISPLAY_DEVICE_Unmanaged unmanaged)
    {
        return new DISPLAY_DEVICE
        {
            cb = unmanaged.cb,
            DeviceName = Utf16StringMarshaller.ConvertToManaged(unmanaged.DeviceName),
            DeviceString = Utf16StringMarshaller.ConvertToManaged(unmanaged.DeviceString),
            StateFlags = (DisplayDeviceStateFlags)unmanaged.StateFlags,
            DeviceID = Utf16StringMarshaller.ConvertToManaged(unmanaged.DeviceID),
            DeviceKey = Utf16StringMarshaller.ConvertToManaged(unmanaged.DeviceKey)
        };
    }

    public static DISPLAY_DEVICE_Unmanaged ConvertToUnmanaged(DISPLAY_DEVICE managed)
    {
        return new DISPLAY_DEVICE_Unmanaged
        {
            cb = managed.cb,
            DeviceName = Utf16StringMarshaller.ConvertToUnmanaged(managed.DeviceName),
            DeviceString = Utf16StringMarshaller.ConvertToUnmanaged(managed.DeviceString),
            StateFlags = (uint)managed.StateFlags,
            DeviceID = Utf16StringMarshaller.ConvertToUnmanaged(managed.DeviceID),
            DeviceKey = Utf16StringMarshaller.ConvertToUnmanaged(managed.DeviceKey)
        };
    }

    public static unsafe void Free(DISPLAY_DEVICE_Unmanaged unmanaged)
    {
        Utf16StringMarshaller.Free(unmanaged.DeviceName);
        Utf16StringMarshaller.Free(unmanaged.DeviceString);
        Utf16StringMarshaller.Free(unmanaged.DeviceID);
        Utf16StringMarshaller.Free(unmanaged.DeviceKey);
    }
}

Calling code:

public static DISPLAY_DEVICE GetPrimaryDisplay()
{
    uint id = 0;
    while (true)
    {
        DISPLAY_DEVICE d = DISPLAY_DEVICE.Create();

        bool done = EnumDisplayDevices(null, id, ref d, 0);

        if ((d.StateFlags & DisplayDeviceStateFlags.PrimaryDevice) == DisplayDeviceStateFlags.PrimaryDevice)
        {
            return d;
        }

        if (done)
            break;

        id++;
    }

    return default;
}

public static DISPLAY_DEVICE GetPrimaryDisplay()
{
    uint id = 0;
    while (true)
    {
        DISPLAY_DEVICE d = DISPLAY_DEVICE.Create();

        bool done = EnumDisplayDevices(null, id, ref d, 0);

        if ((d.StateFlags & DisplayDeviceStateFlags.PrimaryDevice) == DisplayDeviceStateFlags.PrimaryDevice)
        {
            return d;
        }

        if (done)
            break;

        id++;
    }

    return default;
}

15 replies

CC#

•Created by nathanAjacobs on 2/7/2024 in #help

What exactly do these limitations mean for NativeAOT?

- No C++/CLI. - Windows: No built-in COM From the docs: https://learn.microsoft.com/en-us/dotnet/core/deploying/native-aot/?tabs=net8plus%2Cwindows#limitations-of-native-aot-deployment

24 replies

CC#

•Created by nathanAjacobs on 1/19/2024 in #help

Optional parameters with dependency injection

Is it possible to have an optional parameter for a constructor with dependency injection. I know that dependency injection usually it implies it is a required dependency, but for example if the only dependency is an ILogger, then I don't really care if one was registered or not. EDIT: Changed ILogger<Test> to be nullable

public class Test
{
    private readonly ILogger<Test>? _logger;

    public Test(ILogger<Test>? logger = null) // does this work?
    {
        _logger = logger
    }

    public void DoSomething()
    {
        _logger?.LogInformation("Doing something...");
    }
}

public class Test
{
    private readonly ILogger<Test>? _logger;

    public Test(ILogger<Test>? logger = null) // does this work?
    {
        _logger = logger
    }

    public void DoSomething()
    {
        _logger?.LogInformation("Doing something...");
    }
}

10 replies

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