相关疑难解决方法(0)

我处于这样一种情况,我想要实例化一个将在运行时确定的类型的对象.我还需要对该类型执行显式转换.

像这样的东西:

static void castTest(myEnum val)
{
    //Call a native function that returns a pointer to a structure
    IntPtr = someNativeFunction(..params..);

    //determine the type of the structure based on the enum value
    Type structType = getTypeFromEnum(val);

    structType myStruct = (structType)Marshal.PtrToStructure(IntPtr, structType);
}

这显然不是有效的代码,但我希望它传达了我想要做的事情的本质.我实际工作的方法必须在~35种不同的类型上执行编组操作.我有几个其他方法需要使用相同的类型集来做类似的事情.所以,我想从这些方法中分离出类型决定逻辑,这样我只需要编写一次,这样方法就可以保持清晰和可读.

我必须承认自己是设计界的新手.有谁能建议一个很好的方法解决这个问题？我怀疑可能有一个我不知道的合适的设计模式.

我正在尝试将某种类型的对象强制转换为它使用的接口Convert.ChangeType(),但是InvalidCastException由于该对象必须实现IConvertible,所以会抛出一个对象.

类型:

public IDocumentSet : IQueryable {}

public IDocumentSet<TDocument> : IDocumentSet, IQueryable<TDocument> {}

public XmlDocumentSet<TDocument> : IDocumentSet<TDocument> {}

从发生错误的代码中摘录:

private readonly ConcurrentDictionary<Type, IDocumentSet> _openDocumentSets = new ConcurrentDictionary<Type, IDocumentSet>();

public void Commit()
{
    if (_isDisposed)
        throw new ObjectDisposedException(nameof(IDocumentStore));

    if (!_openDocumentSets.Any())
        return;

    foreach (var openDocumentSet in _openDocumentSets)
    {
        var documentType    = openDocumentSet.Key;
        var documentSet     = openDocumentSet.Value;

        var fileName        = GetDocumentSetFileName(documentType);
        var documentSetPath = Path.Combine(FolderPath, fileName);

        using (var stream = new FileStream(documentSetPath, FileMode.Create, …

我想实现一个通用的运行时类型转换函数,它使用.Net TypeConverters来进行转换.

有谁知道如何查找和调用特定类型的TypeConverter？

考虑一下这个C#示例:

//
// Convert obj to the type specified by 'toType'.
// 
object ConvertTo(object obj, Type toType)
{
    if (TypeIsEqualOrDerivesFrom(obj.GetType(), toType)) <-- I know how to implement this.
    {
        // The type of obj is the same as the type specified by 'toType' or
        // the type of obj derives from the type specified by 'toType'.
        return obj;
    }

    if (TypeConverterExists(obj.GetType(), toType) <-- How do I implement this?
    {
        // There exists a type convertor that is …

我有以下类Point和Class2.我的目的是在Class2中检索所有Points实例以将它们存储在List中.

public class Point
    {
        int x;
        int y;
        string col;

        public Point(int abs, int ord, string clr)
        {
            this.x = abs;
            this.y = ord;
            this.col = clr;
        }

        public string toColor()
        {
            return this.col;
        }

        public int Addition()
        {
            return (this.x + this.y);
        }
    }

class Class2
    {
        int test;
        Point pt1;
        Point pt2;
        Point pt3;
        List<Point> listPt = new List<Point>() { };

        public Class2()
        {
            test = 100;
            this.pt1 = new Point(2, 3, "red");
            this.pt2 = new Point(1, …

我想知道是否有一种方法可以使用system.reflection转换为精确类型,这样你就可以避免进行显式转换

(System.DateTime)

例如

假设我有一个像这样的词典

Dictionary<propName, Dictionary<object, Type>>

并假设我迭代一个对象道具列表

foreach (var prop in @object.GetType().GetProperties())
{
       object propValue = propInfo.GetValue(@object, null);
       string propName = propInfo.Name;

       Dictionary<object, Type> typeDictionary = new Dictionary<object, Type>();
       Type propType = propInfo.GetValue(@object, null).GetType();
       typeDictionary[propValue ] = propType ;

       propsDictionary[propInfo.Name] = propValue;
}

我想做类似的事情,使用类似的东西投射到精确类型

// this part is only for guidelines 
// it should obtain the exact Type 
// ... but it returns a string of that type Namespace.Type
Type exactType = Dictionary[enumOfPropName][someValue] 
// this part should know the …