AspectGenerator 0.0.3-preview

This is a prerelease version of AspectGenerator.
There is a newer prerelease version of this package available.
See the version list below for details.
dotnet add package AspectGenerator --version 0.0.3-preview                
NuGet\Install-Package AspectGenerator -Version 0.0.3-preview                
This command is intended to be used within the Package Manager Console in Visual Studio, as it uses the NuGet module's version of Install-Package.
<PackageReference Include="AspectGenerator" Version="0.0.3-preview" />                
For projects that support PackageReference, copy this XML node into the project file to reference the package.
paket add AspectGenerator --version 0.0.3-preview                
#r "nuget: AspectGenerator, 0.0.3-preview"                
#r directive can be used in F# Interactive and Polyglot Notebooks. Copy this into the interactive tool or source code of the script to reference the package.
// Install AspectGenerator as a Cake Addin
#addin nuget:?package=AspectGenerator&version=0.0.3-preview&prerelease

// Install AspectGenerator as a Cake Tool
#tool nuget:?package=AspectGenerator&version=0.0.3-preview&prerelease                

Aspect Generator

The Aspect Generator can help you easily create your own aspects.

[!WARNING] Interceptors are an experimental compiler feature planned to ship in .NET 8 (with support for C# only). The feature may be subject to breaking changes or removal in a future release.

Download and Install

Install nuget

> dotnet add package AspectGenerator

Modify your project file

<PropertyGroup>
    ...
    <LangVersion>preview</LangVersion>
    <InterceptorsPreviewNamespaces>$(InterceptorsPreviewNamespaces);AspectGenerator</InterceptorsPreviewNamespaces>
</PropertyGroup>

OpenTelemetry Aspect example

Create OpenTelemetryFactory and Metrics aspect:

using System;
using System.Diagnostics;

using OpenTelemetry;
using OpenTelemetry.Resources;
using OpenTelemetry.Trace;

namespace AspectGenerator
{
    /// <summary>
    /// Initializes OpenTelemetry.
    /// </summary>
    static class OpenTelemetryFactory
    {
        public static TracerProvider? Create()
        {
            return Sdk.CreateTracerProviderBuilder()
                .SetResourceBuilder(ResourceBuilder.CreateDefault().AddService("MySample"))
                .AddSource("Sample.Aspect")
                .AddConsoleExporter()
                .Build();
        }
    }

    /// <summary>
    /// Metrics aspect.
    /// </summary>
    [Aspect(
        // Specify the name of the method used in the 'using' statement
        // that returns an IDisposable object.
        OnUsing = nameof(OnUsing)
        )]
    [AttributeUsage(AttributeTargets.Method, Inherited = false, AllowMultiple = false)]
    sealed class MetricsAttribute : Attribute
    {
        static readonly ActivitySource _activitySource = new("Sample.Aspect");

        public static Activity? OnUsing(InterceptInfo info)
        {
            return _activitySource.StartActivity(info.MemberInfo.Name);
        }
    }
}

Use it:

using System;
using System.Threading;

using Aspects;

namespace OpenTelemetryAspect
{
    static class Program
    {
        static void Main()
        {
            using var _ = OpenTelemetryFactory.Create();

            Method1();
            Method2();
            Method1();
        }

        [Metrics]
        public static void Method1()
        {
            Thread.Sleep(100);
        }

        [Metrics]
        public static void Method2()
        {
            Thread.Sleep(200);
        }
    }
}

Application output:

Activity.TraceId:            d47417e726824c7b39055efb4685a9dd
Activity.SpanId:             12fbf29f5b622e13
Activity.TraceFlags:         Recorded
Activity.ActivitySourceName: Sample.Aspect
Activity.DisplayName:        Method1
Activity.Kind:               Internal
Activity.StartTime:          2023-11-22T00:50:15.9079068Z
Activity.Duration:           00:00:00.1016180
Resource associated with Activity:
    service.name: MySample
    service.instance.id: 86dbd377-c850-42a3-b878-be07de30faf1
    telemetry.sdk.name: opentelemetry
    telemetry.sdk.language: dotnet
    telemetry.sdk.version: 1.6.0

Activity.TraceId:            b90735bfb52cb0b52a504d02bc5ead2e
Activity.SpanId:             75109ef3af25a3e9
Activity.TraceFlags:         Recorded
Activity.ActivitySourceName: Sample.Aspect
Activity.DisplayName:        Method2
Activity.Kind:               Internal
Activity.StartTime:          2023-11-22T00:50:16.0360160Z
Activity.Duration:           00:00:00.2058166
Resource associated with Activity:
    service.name: MySample
    service.instance.id: 86dbd377-c850-42a3-b878-be07de30faf1
    telemetry.sdk.name: opentelemetry
    telemetry.sdk.language: dotnet
    telemetry.sdk.version: 1.6.0

Activity.TraceId:            e9653008f381b6330a8e538e02b7a61d
Activity.SpanId:             be3d7cd1d4376bd7
Activity.TraceFlags:         Recorded
Activity.ActivitySourceName: Sample.Aspect
Activity.DisplayName:        Method1
Activity.Kind:               Internal
Activity.StartTime:          2023-11-22T00:50:16.2517480Z
Activity.Duration:           00:00:00.1135186
Resource associated with Activity:
    service.name: MySample
    service.instance.id: 86dbd377-c850-42a3-b878-be07de30faf1
    telemetry.sdk.name: opentelemetry
    telemetry.sdk.language: dotnet
    telemetry.sdk.version: 1.6.0

Generated code:

// <auto-generated/>
#pragma warning disable
#nullable enable

using System;

using SR  = System.Reflection;
using SLE = System.Linq.Expressions;
using SCG = System.Collections.Generic;

namespace Aspects
{
    static partial class Interceptors
    {
        static SR.MethodInfo GetMethodInfo(SLE.Expression expr)
        {
            return expr switch
            {
                SLE.MethodCallExpression mc => mc.Method,
                _                           => throw new InvalidOperationException()
            };
        }

        static SR.MethodInfo MethodOf<T>(SLE.Expression<Func<T>> func) => GetMethodInfo(func.Body);
        static SR.MethodInfo MethodOf   (SLE.Expression<Action>  func) => GetMethodInfo(func.Body);

        static SR. MemberInfo                 Method1_Interceptor_MemberInfo        = MethodOf(() => OpenTelemetryAspect.Program.Method1());
        static SCG.Dictionary<string,object?> Method1_Interceptor_AspectArguments_0 = new ()
        {
        };
        //
        /// <summary>
        /// Intercepts OpenTelemetryAspect.Program.Method1().
        /// </summary>
        //
        // Intercepts Method1().
        [System.Runtime.CompilerServices.InterceptsLocation(@"P:\AspectGenerator\Examples\OpenTelemetryAspect\Program.cs", line: 14, character: 4)]
        //
        // Intercepts Method1().
        [System.Runtime.CompilerServices.InterceptsLocation(@"P:\AspectGenerator\Examples\OpenTelemetryAspect\Program.cs", line: 16, character: 4)]
        //
        [System.Runtime.CompilerServices.CompilerGenerated]
        //[System.Diagnostics.DebuggerStepThrough]
        public static void Method1_Interceptor()
        {
            // Aspects.MetricsAttribute
            //
            var __info__0 = new Aspects.InterceptInfo<Void>
            {
                MemberInfo      = Method1_Interceptor_MemberInfo,
                AspectType      = typeof(Aspects.MetricsAttribute),
                AspectArguments = Method1_Interceptor_AspectArguments_0,
            };

            using (Aspects.MetricsAttribute.OnUsing(__info__0))
            {
                OpenTelemetryAspect.Program.Method1();
            }
        }

        static SR. MemberInfo                 Method2_Interceptor_MemberInfo        = MethodOf(() => OpenTelemetryAspect.Program.Method2());
        static SCG.Dictionary<string,object?> Method2_Interceptor_AspectArguments_0 = new ()
        {
        };
        //
        /// <summary>
        /// Intercepts OpenTelemetryAspect.Program.Method2().
        /// </summary>
        //
        // Intercepts Method2().
        [System.Runtime.CompilerServices.InterceptsLocation(@"P:\AspectGenerator\Examples\OpenTelemetryAspect\Program.cs", line: 15, character: 4)]
        //
        [System.Runtime.CompilerServices.CompilerGenerated]
        //[System.Diagnostics.DebuggerStepThrough]
        public static void Method2_Interceptor()
        {
            // Aspects.MetricsAttribute
            //
            var __info__0 = new Aspects.InterceptInfo<Void>
            {
                MemberInfo      = Method2_Interceptor_MemberInfo,
                AspectType      = typeof(Aspects.MetricsAttribute),
                AspectArguments = Method2_Interceptor_AspectArguments_0,
            };

            using (Aspects.MetricsAttribute.OnUsing(__info__0))
            {
                OpenTelemetryAspect.Program.Method2();
            }
        }
    }
}

More advanced vertion of the Metrics aspect can also set activity status.

[Aspect(
    OnUsing   = nameof(OnUsing),
    OnFinally = nameof(OnFinally)
    )]
[AttributeUsage(AttributeTargets.Method, Inherited = false, AllowMultiple = false)]
sealed class MetricsAttribute : Attribute
{
    static readonly ActivitySource _activitySource = new("Sample.Aspect");

    public static Activity? OnUsing(InterceptInfo info)
    {
        var activity = _activitySource.StartActivity(info.MemberInfo.Name);

        info.Tag = activity;

        return activity;
    }

    public static void OnFinally(InterceptInfo info)
    {
        if (info is { Tag: Activity activity, Exception: var ex })
            activity.SetStatus(ex is null ? ActivityStatusCode.Ok : ActivityStatusCode.Error);
    }
}
Product Compatible and additional computed target framework versions.
.NET net5.0 was computed.  net5.0-windows was computed.  net6.0 was computed.  net6.0-android was computed.  net6.0-ios was computed.  net6.0-maccatalyst was computed.  net6.0-macos was computed.  net6.0-tvos was computed.  net6.0-windows was computed.  net7.0 was computed.  net7.0-android was computed.  net7.0-ios was computed.  net7.0-maccatalyst was computed.  net7.0-macos was computed.  net7.0-tvos was computed.  net7.0-windows was computed.  net8.0 was computed.  net8.0-android was computed.  net8.0-browser was computed.  net8.0-ios was computed.  net8.0-maccatalyst was computed.  net8.0-macos was computed.  net8.0-tvos was computed.  net8.0-windows was computed. 
.NET Core netcoreapp2.0 was computed.  netcoreapp2.1 was computed.  netcoreapp2.2 was computed.  netcoreapp3.0 was computed.  netcoreapp3.1 was computed. 
.NET Standard netstandard2.0 is compatible.  netstandard2.1 was computed. 
.NET Framework net461 was computed.  net462 was computed.  net463 was computed.  net47 was computed.  net471 was computed.  net472 was computed.  net48 was computed.  net481 was computed. 
MonoAndroid monoandroid was computed. 
MonoMac monomac was computed. 
MonoTouch monotouch was computed. 
Tizen tizen40 was computed.  tizen60 was computed. 
Xamarin.iOS xamarinios was computed. 
Xamarin.Mac xamarinmac was computed. 
Xamarin.TVOS xamarintvos was computed. 
Xamarin.WatchOS xamarinwatchos was computed. 
Compatible target framework(s)
Included target framework(s) (in package)
Learn more about Target Frameworks and .NET Standard.

NuGet packages

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Version Downloads Last updated
0.0.9-preview 138 12/28/2023
0.0.8-preview 98 12/13/2023
0.0.7-preview 73 12/12/2023
0.0.5-preview 95 12/4/2023
0.0.4-preview 74 11/27/2023
0.0.3-preview 70 11/23/2023
0.0.1-preview 58 11/22/2023