* Added new namespace "Aspects" and types dedicated for aspected handlers processing, including Pre\Post processors

* Added new DescriptorAspectsSet class, used for mamanging and executing aspects of handlers
* Processors can prevent handlers execution using Result.Fault()
* Added field to DescribedHandlerInfo for getting descriptor from which this handler was described
* Removed unused reflection extension methods

Telegrator.Hosting.Web/TelegramBotWebOptions.cs

@@ -1,6 +1,5 @@
 using Microsoft.AspNetCore.Builder;
 using Microsoft.Extensions.Options;
-using System.Diagnostics.CodeAnalysis;
 
 namespace Telegrator.Hosting.Web
 {

Telegrator/Aspects/AfterExecutionAttribute.cs

@@ -0,0 +1,8 @@
+namespace Telegrator.Aspects
+{
+    [AttributeUsage(AttributeTargets.Class, AllowMultiple = false)]
+    public class AfterExecutionAttribute<T> : Attribute where T : IPostProcessor
+    {
+        public Type ProcessorType => typeof(T);
+    }
+}

Telegrator/Aspects/BeforeExecutionAttribute.cs

@@ -0,0 +1,8 @@
+namespace Telegrator.Aspects
+{
+    [AttributeUsage(AttributeTargets.Class, AllowMultiple = false)]
+    public class BeforeExecutionAttribute<T> : Attribute where T : IPreProcessor
+    {
+        public Type ProcessorType => typeof(T);
+    }
+}

Telegrator/Aspects/IPostProcessor.cs.cs

@@ -0,0 +1,13 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+using Telegrator.Handlers;
+using Telegrator.Handlers.Components;
+
+namespace Telegrator.Aspects
+{
+    public interface IPostProcessor
+    {
+        public Task<Result> AfterExecution(IHandlerContainer container);
+    }
+}

Telegrator/Aspects/IPreProcessor.cs

@@ -0,0 +1,13 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+using Telegrator.Handlers;
+using Telegrator.Handlers.Components;
+
+namespace Telegrator.Aspects
+{
+    public interface IPreProcessor
+    {
+        public Task<Result> BeforeExecution(IHandlerContainer container);
+    }
+}

Telegrator/Attributes/UpdateHandlerAttribute.cs

@@ -9,10 +9,38 @@ namespace Telegrator.Attributes
     /// Provides a type-safe way to associate handler types with specific update types and importance settings.
     /// </summary>
     /// <typeparam name="T">The type of the update handler that this attribute is applied to.</typeparam>
-    /// <param name="updateType">The type of update that this handler can process.</param>
+    public abstract class UpdateHandlerAttribute<T> : UpdateHandlerAttributeBase where T : UpdateHandlerBase
-    /// <param name="importance">The importance level for this handler (default: 0 for unlimited).</param>
-    public abstract class UpdateHandlerAttribute<T>(UpdateType updateType, int importance = 0)
-        : UpdateHandlerAttributeBase([typeof(T)], updateType, importance) where T : UpdateHandlerBase
     {
+        /// <summary>
+        /// Initializes new instance of <see cref="UpdateHandlerAttribute{T}"/>
+        /// </summary>
+        /// <param name="updateType">The type of update that this handler can process.</param>
+        protected UpdateHandlerAttribute(UpdateType updateType)
+            : base([typeof(T)], updateType, 0) { }
+
+        /// <summary>
+        /// Initializes new instance of <see cref="UpdateHandlerAttribute{T}"/>
+        /// </summary>
+        /// <param name="updateType">The type of update that this handler can process.</param>
+        /// <param name="importance">The importance level for this handler</param>
+        protected UpdateHandlerAttribute(UpdateType updateType, int importance)
+            : base([typeof(T)], updateType, importance) { }
+
+        /// <summary>
+        /// Initializes new instance of <see cref="UpdateHandlerAttribute{T}"/>
+        /// </summary>
+        /// <param name="types">Additional suported types.</param>
+        /// <param name="updateType">The type of update that this handler can process.</param>
+        protected UpdateHandlerAttribute(Type[] types, UpdateType updateType)
+            : base([..types, typeof(T)], updateType, 0) { }
+
+        /// <summary>
+        /// Initializes new instance of <see cref="UpdateHandlerAttribute{T}"/>
+        /// </summary>
+        /// <param name="types">Additional suported types.</param>
+        /// <param name="updateType">The type of update that this handler can process.</param>
+        /// <param name="importance">The importance level for this handler</param>
+        protected UpdateHandlerAttribute(Type[] types, UpdateType updateType, int importance)
+            : base([.. types, typeof(T)], updateType, importance) { }
     }
 }

Telegrator/MadiatorCore/Descriptors/DescribedHandlerInfo.cs

@@ -12,6 +12,11 @@ namespace Telegrator.MadiatorCore.Descriptors
     /// </summary>
     public class DescribedHandlerInfo
     {
+        /// <summary>
+        /// descriptor from that handler was described from
+        /// </summary>
+        public readonly HandlerDescriptor From;
+
         /// <summary>
         /// The update router associated with this handler.
         /// </summary>
@@ -60,13 +65,15 @@ namespace Telegrator.MadiatorCore.Descriptors
         /// <summary>
         /// Initializes a new instance of the <see cref="DescribedHandlerInfo"/> class.
         /// </summary>
+        /// <param name="fromDescriptor">descriptor from that handler was described from</param>
         /// <param name="updateRouter">The update router.</param>
         /// <param name="client">The Telegram bot client.</param>
         /// <param name="handlerInstance">The handler instance.</param>
         /// <param name="filterContext">The filter execution context.</param>
         /// <param name="displayString">Optional display string.</param>
-        public DescribedHandlerInfo(IUpdateRouter updateRouter, ITelegramBotClient client, UpdateHandlerBase handlerInstance, FilterExecutionContext<Update> filterContext, string? displayString)
+        public DescribedHandlerInfo(HandlerDescriptor fromDescriptor, IUpdateRouter updateRouter, ITelegramBotClient client, UpdateHandlerBase handlerInstance, FilterExecutionContext<Update> filterContext, string? displayString)
         {
+            From = fromDescriptor;
             UpdateRouter = updateRouter;
             Client = client;
             HandlerInstance = handlerInstance;
@@ -90,7 +97,26 @@ namespace Telegrator.MadiatorCore.Descriptors
             try
             {
                 HandlerContainer = GetContainer(UpdateRouter.AwaitingProvider, this);
-                return await HandlerInstance.Execute(HandlerContainer, cancellationToken);
+
+                if (From.Aspects != null)
+                {
+                    Result preResult = await From.Aspects.ExecutePre(HandlerInstance, HandlerContainer);
+                    if (!preResult.Positive)
+                        return preResult;
+                }
+
+                Result execResult = await HandlerInstance.Execute(HandlerContainer, cancellationToken);
+                if (!execResult.Positive)
+                    return execResult;
+
+                if (From.Aspects != null)
+                {
+                    Result postResult = await From.Aspects.ExecutePost(HandlerInstance, HandlerContainer);
+                    if (!postResult.Positive)
+                        return postResult;
+                }
+
+                return Result.Ok();
             }
             catch (OperationCanceledException)
             {

Telegrator/MadiatorCore/Descriptors/DescriptorAspectsSet.cs

@@ -0,0 +1,63 @@
+using Telegrator.Aspects;
+using Telegrator.Handlers;
+using Telegrator.Handlers.Components;
+
+namespace Telegrator.MadiatorCore.Descriptors
+{
+    public sealed class DescriptorAspectsSet
+    {
+        public bool SelfPre { get; private set; }
+
+        public bool SelfPost { get; private set; }
+
+        public Type? TypedPre { get; private set; }
+
+        public Type? TypedPost { get; private set; }
+
+        public DescriptorAspectsSet(bool selfPre, Type? typedPre, bool selfPost, Type? typedPost)
+        {
+            SelfPre = selfPre;
+            SelfPost = selfPost;
+            TypedPre = typedPre;
+            TypedPost = typedPost;
+        }
+
+        public async Task<Result> ExecutePre(UpdateHandlerBase handler, IHandlerContainer container)
+        {
+            if (SelfPre)
+            {
+                if (handler is not IPreProcessor preProcessor)
+                    throw new InvalidOperationException();
+
+                return await preProcessor.BeforeExecution(container);
+            }
+
+            if (TypedPre != null)
+            {
+                IPreProcessor preProcessor = (IPreProcessor)Activator.CreateInstance(TypedPre);
+                return await preProcessor.BeforeExecution(container);
+            }
+
+            return Result.Ok();
+        }
+
+        public async Task<Result> ExecutePost(UpdateHandlerBase handler, IHandlerContainer container)
+        {
+            if (SelfPost)
+            {
+                if (handler is not IPostProcessor postProcessor)
+                    throw new InvalidOperationException();
+
+                return await postProcessor.AfterExecution(container);
+            }
+
+            if (TypedPost != null)
+            {
+                IPostProcessor postProcessor = (IPostProcessor)Activator.CreateInstance(TypedPost);
+                return await postProcessor.AfterExecution(container);
+            }
+
+            return Result.Ok();
+        }
+    }
+}

Telegrator/MadiatorCore/Descriptors/HandlerDescriptor.cs

@@ -76,7 +76,13 @@ namespace Telegrator.MadiatorCore.Descriptors
         /// <summary>
         /// The set of filters associated with this handler.
         /// </summary>
-        public DescriptorFiltersSet Filters
+        public DescriptorFiltersSet? Filters
+        {
+            get;
+            protected set;
+        }
+
+        public DescriptorAspectsSet? Aspects
         {
             get;
             protected set;
@@ -154,6 +160,7 @@ namespace Telegrator.MadiatorCore.Descriptors
             UpdateType = handlerAttribute.Type;
             Indexer = handlerAttribute.GetIndexer();
             Filters = new DescriptorFiltersSet(handlerAttribute, stateKeeperAttribute, filters);
+            Aspects = HandlerInspector.GetAspects(handlerType);
             DisplayString = HandlerInspector.GetDisplayName(handlerType);
         }
 

Telegrator/MadiatorCore/Descriptors/HandlerInspector.cs

@@ -2,6 +2,7 @@
 using System.Reflection;
 using Telegram.Bot.Types;
 using Telegram.Bot.Types.Enums;
+using Telegrator.Aspects;
 using Telegrator.Attributes.Components;
 using Telegrator.Filters.Components;
 
@@ -80,5 +81,29 @@ namespace Telegrator.MadiatorCore.Descriptors
                 }
             }
         }
+
+        public static DescriptorAspectsSet GetAspects(Type handlerType)
+        {
+            bool selfPre = handlerType.GetInterface(nameof(IPreProcessor)) != null;
+            bool selfPost = handlerType.GetInterface(nameof(IPostProcessor)) != null;
+            Type? typedPre = null;
+            Type? typedPost = null;
+
+            if (!selfPre)
+            {
+                Attribute? preAttr = handlerType.GetCustomAttribute(typeof(BeforeExecutionAttribute<>));
+                if (preAttr != null)
+                    typedPre = preAttr.GetType().GetGenericArguments()[0];
+            }
+
+            if (!selfPost)
+            {
+                Attribute? postAttr = handlerType.GetCustomAttribute(typeof(AfterExecutionAttribute<>));
+                if (postAttr != null)
+                    typedPre = postAttr.GetType().GetGenericArguments()[0];
+            }
+
+            return new DescriptorAspectsSet(selfPre, typedPre, selfPost, typedPost);
+        }
     }
 }

Telegrator/Polling/UpdateRouter.cs

@@ -223,11 +223,11 @@ namespace Telegrator.Polling
             };
 
             FilterExecutionContext<Update> filterContext = new FilterExecutionContext<Update>(_botInfo, update, update, data, []);
-            if (!descriptor.Filters.Validate(filterContext))
+            if (descriptor.Filters != null && !descriptor.Filters.Validate(filterContext))
                 return null;
 
             UpdateHandlerBase handlerInstance = provider.GetHandlerInstance(descriptor, cancellationToken);
-            return new DescribedHandlerInfo(updateRouter, client, handlerInstance, filterContext, descriptor.DisplayString);
+            return new DescribedHandlerInfo(descriptor, updateRouter, client, handlerInstance, filterContext, descriptor.DisplayString);
         }
 
         /// <summary>

Telegrator/Providers/HandlersCollection.cs

@@ -68,7 +68,7 @@ namespace Telegrator.Providers
         public virtual IHandlersCollection AddDescriptor(HandlerDescriptor descriptor)
         {
             if (MustHaveParameterlessCtor && !descriptor.HandlerType.HasParameterlessCtor())
-                throw new Exception();
+                throw new Exception("This handler (" + descriptor.HandlerType.FullName + "), must contain constructor without parameters.");
 
             _allowedTypes.Union(descriptor.UpdateType);
             MightAwaitAttribute[] mightAwaits = descriptor.HandlerType.GetCustomAttributes<MightAwaitAttribute>().ToArray();

Telegrator/TypesExtensions.cs

@@ -886,6 +886,7 @@ namespace Telegrator
         public static bool HasParameterlessCtor(this Type type)
             => type.GetConstructors().Any(ctor => ctor.GetParameters().Length == 0);
 
+        /*
         /// <summary>
         /// Invokes a "<paramref name="methodName"/>" method of an object
         /// </summary>
@@ -948,6 +949,7 @@ namespace Telegrator
         /// <returns></returns>
         public static T? InvokeGenericMethod<T>(this object obj, string methodName, Type[] genericParameters, params object[]? parameters)
             => (T?)obj.GetType().GetMethod(methodName).InvokeGenericMethod(obj, genericParameters, parameters);
+        */
 
         /// <summary>
         /// Checks is <paramref name="obj"/> has public properties