Jason_Bjorn Posts - Answer Overflow

Jason_Bjorn

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CC#

•Created by Jason_Bjorn on 8/23/2024 in #help

✅ Avalonia - Can't see anything even though control is styled

3 replies

CC#

•Created by Jason_Bjorn on 8/16/2024 in #help

Avalonia IconPath not showing up

9 replies

CC#

•Created by Jason_Bjorn on 8/12/2024 in #help

✅ Avalonia - Textbox text changed

How can I react if the text in a TextBox https://reference.avaloniaui.net/api/Avalonia.Controls/TextBox/ changes. Right now I am using KeyUp but that doesn't handle things like backspace

2 replies

CC#

•Created by Jason_Bjorn on 8/9/2024 in #help

✅ A nicer way to create an on-demand property?

Is there a nicer way to create sum here?

Foo f = new() {
    X = 3,
    Y = 4
};

f.Dump();

class Foo
{
    public required int X { get; init; }
    public required int Y { get; init; }
    private int? sum = null;

    public int Sum
    {
        get
        {
            Console.WriteLine("Calculating Sum");
            sum ??= X + Y;
            return sum.Value;
        }
    }
}

Foo f = new() {
    X = 3,
    Y = 4
};

f.Dump();

class Foo
{
    public required int X { get; init; }
    public required int Y { get; init; }
    private int? sum = null;

    public int Sum
    {
        get
        {
            Console.WriteLine("Calculating Sum");
            sum ??= X + Y;
            return sum.Value;
        }
    }
}

14 replies

CC#

•Created by Jason_Bjorn on 8/9/2024 in #help

✅ Generic function with conditional type based logic inside

How can I make something like this work? I want the user to either be able to get a list of ints or strings.

List<int> lInt = Foo<int>();
List<string> lString = Foo<string>();

// Should either returns a List of Ints or strings
List<T> Foo<T>()
{
    List<T> list = new();

    for (int i = 0; i < 10; i++)
    {
        T valueToAdd;
        if (typeof(T) == typeof(int))
        {
            valueToAdd = i;
        }
        else if (typeof(T) == typeof(string))
        {
            valueToAdd = i.ToString();
        }
        else {
            throw new InvalidOperationException($"Invalid type {typeof(T)}");
        }
        list.Add(valueToAdd);
    }
    return list;
}

List<int> lInt = Foo<int>();
List<string> lString = Foo<string>();

// Should either returns a List of Ints or strings
List<T> Foo<T>()
{
    List<T> list = new();

    for (int i = 0; i < 10; i++)
    {
        T valueToAdd;
        if (typeof(T) == typeof(int))
        {
            valueToAdd = i;
        }
        else if (typeof(T) == typeof(string))
        {
            valueToAdd = i.ToString();
        }
        else {
            throw new InvalidOperationException($"Invalid type {typeof(T)}");
        }
        list.Add(valueToAdd);
    }
    return list;
}

31 replies

CC#

•Created by Jason_Bjorn on 8/8/2024 in #help

✅ Benchmarks not running

2 replies

CC#

•Created by Jason_Bjorn on 8/1/2024 in #help

✅ Custom `IComparer` adds so much overhead

Is there a way I can avoid having to make a whole new class for the IComparer interface here? https://dotnetfiddle.net/yRh9YN

using System.Collections.Generic;
using System;
#nullable enable

SortedList<string, int> l = new(new RomanNumeralComparer())
{
    // shuffled on purpose
    { "V", 5 },
    { "I", 1 },
    { "L", 50 },
    { "X", 10 },
};


// correctly prints in the order of 
// I V X L
foreach (var c in l)
{
    Console.WriteLine(c);
}

// big class for something so small
public class RomanNumeralComparer : IComparer<string>
{
    private readonly string _order = "IVXL";

    public int Compare(string? x, string? y)
    {
        if (x is null && y is null)
        {
            return 0;
        }

        if (x is null)
        {
            return -1;
        }

        if (y is null)
        {
            return 1;
        }

        int xRank = _order.IndexOf(x, StringComparison.InvariantCulture);
        int yRank = _order.IndexOf(y, StringComparison.InvariantCulture);

        return (xRank < yRank) ? -1 : (xRank == yRank) ? 0 : 1;
    }
}

using System.Collections.Generic;
using System;
#nullable enable

SortedList<string, int> l = new(new RomanNumeralComparer())
{
    // shuffled on purpose
    { "V", 5 },
    { "I", 1 },
    { "L", 50 },
    { "X", 10 },
};


// correctly prints in the order of 
// I V X L
foreach (var c in l)
{
    Console.WriteLine(c);
}

// big class for something so small
public class RomanNumeralComparer : IComparer<string>
{
    private readonly string _order = "IVXL";

    public int Compare(string? x, string? y)
    {
        if (x is null && y is null)
        {
            return 0;
        }

        if (x is null)
        {
            return -1;
        }

        if (y is null)
        {
            return 1;
        }

        int xRank = _order.IndexOf(x, StringComparison.InvariantCulture);
        int yRank = _order.IndexOf(y, StringComparison.InvariantCulture);

        return (xRank < yRank) ? -1 : (xRank == yRank) ? 0 : 1;
    }
}

32 replies

CC#

•Created by Jason_Bjorn on 7/22/2024 in #help

✅ Improving code

I have this old method and then I didn't like how repetative the logic was so I put it in a lambda. I was wondering is there a better/more c# idomatic way still?

    // old method
    temp changed by more than 10%
    if (Math.Abs(e.NewTemperature - e.OldTemperature) > 0.10)
    {
        Console.WriteLine("Temperature changed by more than 10%");
    }
    
    if (Math.Abs(e.NewHumidity - e.OldTemperature) > 0.10)
    {
        Console.WriteLine("Humidity changed by more than 10%");
    }

    // new method
    // lambda, static to not capture anything
    static bool isWithinPercentage(double value1, double value2, double decimalPercentage) => (Math.Abs(value1 - value2) <= decimalPercentage);
    if (!isWithinPercentage(e.NewTemperature, e.OldTemperature, 0.10))
    {
        Console.WriteLine("Temperature changed by more than 10%");
    }

    if (!isWithinPercentage(e.NewHumidity, e.OldHumidity, 0.10))
    {
        Console.WriteLine("Humidity changed by more than 10%");

    }

    // old method
    temp changed by more than 10%
    if (Math.Abs(e.NewTemperature - e.OldTemperature) > 0.10)
    {
        Console.WriteLine("Temperature changed by more than 10%");
    }
    
    if (Math.Abs(e.NewHumidity - e.OldTemperature) > 0.10)
    {
        Console.WriteLine("Humidity changed by more than 10%");
    }

    // new method
    // lambda, static to not capture anything
    static bool isWithinPercentage(double value1, double value2, double decimalPercentage) => (Math.Abs(value1 - value2) <= decimalPercentage);
    if (!isWithinPercentage(e.NewTemperature, e.OldTemperature, 0.10))
    {
        Console.WriteLine("Temperature changed by more than 10%");
    }

    if (!isWithinPercentage(e.NewHumidity, e.OldHumidity, 0.10))
    {
        Console.WriteLine("Humidity changed by more than 10%");

    }

3 replies

CC#

•Created by Jason_Bjorn on 7/17/2024 in #help

✅ IL for function vs expression-bodied-function

Why do these two compile to different things?

class Program {
    int Double1(int n) => n + n;

    int Double2(int n) {
        return n + n;
    }
}

class Program {
    int Double1(int n) => n + n;

    int Double2(int n) {
        return n + n;
    }
}

14 replies

CC#

•Created by Jason_Bjorn on 7/14/2024 in #help

✅ Double-Async

Is Method1 double async here?

public static async Task<string> Method1()
    {
        var client = new HttpClient();
        Console.WriteLine("in ");
        var content = await client.GetStringAsync("https://microsoft.com");
        return content;
    }

    public static Task<string> Method2()
    {
        var client = new HttpClient();
        return client.GetStringAsync("https://microsoft.com");
    }

public static async Task<string> Method1()
    {
        var client = new HttpClient();
        Console.WriteLine("in ");
        var content = await client.GetStringAsync("https://microsoft.com");
        return content;
    }

    public static Task<string> Method2()
    {
        var client = new HttpClient();
        return client.GetStringAsync("https://microsoft.com");
    }

46 replies

CC#

•Created by Jason_Bjorn on 7/13/2024 in #help

✅ [AllowedValue] not doing anything

Why is my code allowing the name "Jimmy" ?

using System.ComponentModel.DataAnnotations;

public class Foo
{
    [AllowedValues(new object [] {"Bill", "Bob"}, "Entered illegal name")]
    public string Name { get; set; }
}

class Program
{
    public static void Main()
    {
        Foo f = new()
        {
            Name = "Jimmy" // works ???
        };
    }
}

using System.ComponentModel.DataAnnotations;

public class Foo
{
    [AllowedValues(new object [] {"Bill", "Bob"}, "Entered illegal name")]
    public string Name { get; set; }
}

class Program
{
    public static void Main()
    {
        Foo f = new()
        {
            Name = "Jimmy" // works ???
        };
    }
}

19 replies

CC#

•Created by Jason_Bjorn on 7/8/2024 in #help

✅ LINQ, simple query

Is there something I can do to make this query better (faster, more idiomatic, etc)

public record Course(
    string Title,
    string Category,
    int Number,
    DateOnly PublicationDate,
    TimeSpan Duration)
{
    public static readonly Course[] Catalog =
    [
        new Course(
            Title: "Elements of Geometry",
            Category: "MAT", Number: 101, Duration: TimeSpan.FromHours(3),
            PublicationDate: new DateOnly(2009, 5, 20)),
        new Course(
            Title: "Squaring the Circle",
            Category: "MAT", Number: 102, Duration: TimeSpan.FromHours(7),
            PublicationDate: new DateOnly(2009, 4, 1)),
        new Course(
            Title: "Recreational Organ Transplantation",
            Category: "BIO", Number: 305, Duration: TimeSpan.FromHours(4),
            PublicationDate: new DateOnly(2002, 7, 19)),
        new Course(
            Title: "Hyperbolic Geometry",
            Category: "MAT", Number: 207, Duration: TimeSpan.FromHours(5),
            PublicationDate: new DateOnly(2007, 10, 5)),
        new Course(
            Title: "Oversimplified Data Structures for Demos",
            Category: "CSE", Number: 104, Duration: TimeSpan.FromHours(2),
            PublicationDate: new DateOnly(2023, 11, 8)),
        new Course(
            Title: "Introduction to Human Anatomy and Physiology",
            Category: "BIO", Number: 201, Duration: TimeSpan.FromHours(12),
            PublicationDate: new DateOnly(2001, 4, 11)),
    ];
}

class Program
{
    public static void Main()
    {
        
        // all the courses that are 4hrs or longer grouped by their category. What is shown: Title, Course-Number, duration
        var q = Course.Catalog.Where(course => course.Duration.TotalHours >= 4).GroupBy(course => course.Category, course => new { course.Title, course.Number, course.Duration.TotalHours });
        q.Dump();
    }
}

public record Course(
    string Title,
    string Category,
    int Number,
    DateOnly PublicationDate,
    TimeSpan Duration)
{
    public static readonly Course[] Catalog =
    [
        new Course(
            Title: "Elements of Geometry",
            Category: "MAT", Number: 101, Duration: TimeSpan.FromHours(3),
            PublicationDate: new DateOnly(2009, 5, 20)),
        new Course(
            Title: "Squaring the Circle",
            Category: "MAT", Number: 102, Duration: TimeSpan.FromHours(7),
            PublicationDate: new DateOnly(2009, 4, 1)),
        new Course(
            Title: "Recreational Organ Transplantation",
            Category: "BIO", Number: 305, Duration: TimeSpan.FromHours(4),
            PublicationDate: new DateOnly(2002, 7, 19)),
        new Course(
            Title: "Hyperbolic Geometry",
            Category: "MAT", Number: 207, Duration: TimeSpan.FromHours(5),
            PublicationDate: new DateOnly(2007, 10, 5)),
        new Course(
            Title: "Oversimplified Data Structures for Demos",
            Category: "CSE", Number: 104, Duration: TimeSpan.FromHours(2),
            PublicationDate: new DateOnly(2023, 11, 8)),
        new Course(
            Title: "Introduction to Human Anatomy and Physiology",
            Category: "BIO", Number: 201, Duration: TimeSpan.FromHours(12),
            PublicationDate: new DateOnly(2001, 4, 11)),
    ];
}

class Program
{
    public static void Main()
    {
        
        // all the courses that are 4hrs or longer grouped by their category. What is shown: Title, Course-Number, duration
        var q = Course.Catalog.Where(course => course.Duration.TotalHours >= 4).GroupBy(course => course.Category, course => new { course.Title, course.Number, course.Duration.TotalHours });
        q.Dump();
    }
}

19 replies

CC#

•Created by Jason_Bjorn on 7/3/2024 in #help

✅ Why is the attempted fix still creating a new copy of the dv each time CallDispose is called?

// given, results in "Disposing for first time" being printed 3 times
// static void CallDispose(IDisposable o)
// {
//     o.Dispose();
// }

// attempted fix, still prints "Disposing for first time" 3 times
static void CallDispose<T>(T o) where T : IDisposable
{ 
    o.Dispose();
}

DisposableValue dv = new();
Console.WriteLine("Passing value variable:");
CallDispose(dv);
CallDispose(dv);
CallDispose(dv);

public struct DisposableValue : IDisposable
{
    private bool _disposedYet;

    public void Dispose()
    {
        if (!_disposedYet)
        {
            Console.WriteLine("Disposing for first time");
            _disposedYet = true;
        }
        else
        {
            Console.WriteLine("Was already disposed");
        }
    }
}

// given, results in "Disposing for first time" being printed 3 times
// static void CallDispose(IDisposable o)
// {
//     o.Dispose();
// }

// attempted fix, still prints "Disposing for first time" 3 times
static void CallDispose<T>(T o) where T : IDisposable
{ 
    o.Dispose();
}

DisposableValue dv = new();
Console.WriteLine("Passing value variable:");
CallDispose(dv);
CallDispose(dv);
CallDispose(dv);

public struct DisposableValue : IDisposable
{
    private bool _disposedYet;

    public void Dispose()
    {
        if (!_disposedYet)
        {
            Console.WriteLine("Disposing for first time");
            _disposedYet = true;
        }
        else
        {
            Console.WriteLine("Was already disposed");
        }
    }
}

19 replies

CC#

•Created by Jason_Bjorn on 7/1/2024 in #help

✅ Two methods: struct and non-struct

Why does b.F(42) call the 2nd overload? 42 is a value-type which is what structs are?

public class Base
{
  public virtual void F<T>(T? t) where T : struct { }
  public virtual void F<T>(T? t) { }
}

Base b = new();
int? nullInt = null;
int? nonNullNullableInt = 42;

// These call the 1st overload.
b.F(nullInt);
b.F(nonNullNullableInt);
b.F(default(int?));

// These call the 2nd overload.
b.F(42);
b.F("Hello");
b.F(default(int));

public class Base
{
  public virtual void F<T>(T? t) where T : struct { }
  public virtual void F<T>(T? t) { }
}

Base b = new();
int? nullInt = null;
int? nonNullNullableInt = 42;

// These call the 1st overload.
b.F(nullInt);
b.F(nonNullNullableInt);
b.F(default(int?));

// These call the 2nd overload.
b.F(42);
b.F("Hello");
b.F(default(int));

9 replies

CC#

•Created by Jason_Bjorn on 6/29/2024 in #help

Why `where T: class`

8 replies

CC#

•Created by Jason_Bjorn on 6/27/2024 in #help

LINQ help

I have a collection of ints, how can I take the last three that are bigger than 100? is there a better way than this?

using System;
using System.Linq;

class Program
{
    static void Main()
    {
        int[] numbers = { 80, 120, 110, 90, 10, 140, 150, 50, 22, -800 };
 
        var result = numbers.Where(num => num > 100).Reverse().Take(3).Reverse().ToArray();

        Console.WriteLine("Last 3 elements over 100:");
        foreach (var num in result)
        {
            Console.WriteLine(num);
        }
    }
}

using System;
using System.Linq;

class Program
{
    static void Main()
    {
        int[] numbers = { 80, 120, 110, 90, 10, 140, 150, 50, 22, -800 };
 
        var result = numbers.Where(num => num > 100).Reverse().Take(3).Reverse().ToArray();

        Console.WriteLine("Last 3 elements over 100:");
        foreach (var num in result)
        {
            Console.WriteLine(num);
        }
    }
}

26 replies

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