Jasonnn Posts - Answer Overflow

Jasonnn

•Created by Jasonnn on 3/18/2025 in #help

Nongeneric interfaces and collection classes

In "C#12 In A Nutshell", they say: "As with the interfaces we discussed previously, you usually have a choice of generic or nongeneric versions of each type. In terms of flexibility and performance, the generic classes win, making their nongeneric counterparts redundant except for backward compatibility. This differs from the situation with collection interfaces, for which the nongeneric versions are still occasionally useful." But the only example they gave was for type unification (since you can't cast IEnumerable<int> to IEnumerable<object> for example). Why is that that type unification is useful just for interfaces and not for collection classes themselves? As far as I understand you can't cast int[] to object[] either. Do you have scenarios in mind for which Nongeneric interfaces are useful and nongeneric collection classes are not?

41 replies

CC#

•Created by Jasonnn on 11/12/2024 in #help

Threading and Microsoft.Data.Sqlite

I'm using multithreading. Each thread will make a query to a SQL Database by using a static class. They should all use the same SqliteConnection connection object that is a field of static class SqlDatabase. I feel like there is only one "opening" of the connection, and therefore there shouldn't be any problems of handling "many users" from SQLite perspective. However, I still get an error:

Unhandled exception. System.NullReferenceException: Object reference not set to an instance of an object.
   at Microsoft.Data.Sqlite.SqliteConnection.RemoveCommand(SqliteCommand command)
   at Microsoft.Data.Sqlite.SqliteCommand.Dispose(Boolean disposing)
   at System.ComponentModel.Component.Dispose()

Unhandled exception. System.NullReferenceException: Object reference not set to an instance of an object.
   at Microsoft.Data.Sqlite.SqliteConnection.RemoveCommand(SqliteCommand command)
   at Microsoft.Data.Sqlite.SqliteCommand.Dispose(Boolean disposing)
   at System.ComponentModel.Component.Dispose()

It looks like it tries to dispose several times the same object, and gets me a bit confused as to what is happening. It's probably because all my threads are trying to use the same object (I explain after the MRE why I think that's the case)?

25 replies

CC#

•Created by Jasonnn on 9/9/2024 in #help

✅ Nullable<int> and xUnit

I'm writing unit tests for a method that has int? as a return type. When I do: Assert.Equal(null, parser.GetNumber(myArguments)); xUnit tells me xUnit2003: Do not use Assert. Equal() to check for null value. Use Assert.Null instead. When I do Assert.Null(parser.GetNumber(myArguments)); It tells me xUnit2002: Do not use Assert.Null() on value type 'int'. Remove this assert. What is happening? What should I do?

9 replies

CC#

•Created by Jasonnn on 9/9/2024 in #help

✅ Reading/Writing in Excel with C#

It seems there are plenty of options to read/write .xlsx files (EPPlus, OpenXML, ClosedXML, ...)? Are there some that are "more official" / "better" and that I really should use? Or are they all more or less the same?

43 replies

CC#

•Created by Jasonnn on 8/30/2024 in #help

merge into pattern

63 replies

CC#

•Created by Jasonnn on 8/3/2024 in #help

Relative paths with assemblies calling each other

I have parent_dir/HaploDeep/models/some_files.onnx, parent_dir/HaploDeep/HaploDeep.cs and parent_dir/HaploDeep.Tests/Tests.cs In HaploDeep.cs I want to open models/files.onnx so I do

        private readonly string[] _modelPaths =
        [
            @"models\model_1.onnx",
            @"models\model_2.onnx",
            @"models\model_3.onnx",
            @"models\model_4.onnx",
            @"models\model_5.onnx"
        ];
        // Load them by using the array _modelPaths

        private readonly string[] _modelPaths =
        [
            @"models\model_1.onnx",
            @"models\model_2.onnx",
            @"models\model_3.onnx",
            @"models\model_4.onnx",
            @"models\model_5.onnx"
        ];
        // Load them by using the array _modelPaths

but when I call the unit tests it says System.IO.IOException: Model file models\model_1.onnx does not exists. I tried to do that:

            string basePath = AppDomain.CurrentDomain.BaseDirectory;
            _modelPaths = [
                Path.Combine(basePath, @"models\model_1.onnx"),
                Path.Combine(basePath, @"models\model_2.onnx"),
                Path.Combine(basePath, @"models\model_3.onnx"),
                Path.Combine(basePath, @"models\model_4.onnx"),
                Path.Combine(basePath, @"models\model_5.onnx")
            ];
            // Load them by using the array _modelPaths

            string basePath = AppDomain.CurrentDomain.BaseDirectory;
            _modelPaths = [
                Path.Combine(basePath, @"models\model_1.onnx"),
                Path.Combine(basePath, @"models\model_2.onnx"),
                Path.Combine(basePath, @"models\model_3.onnx"),
                Path.Combine(basePath, @"models\model_4.onnx"),
                Path.Combine(basePath, @"models\model_5.onnx")
            ];
            // Load them by using the array _modelPaths

in HaploDeep.cs But then when running my unit tests I have the same, it thinks the relative paths are relative to HaploDeep.Tests path: System.IO.IOException: Model file C:\...\HaploDeep.Tests\bin\Debug\net8.0\models\model_1.onnx does not exi... I've been using Python for years and if a path was relative in library 1, when library 2 would use library 1, the paths would be relative to library 1; not to library 2. And here I'm really confused. Would really appreciate some help, I've been banging my head on this for the past hour

16 replies

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