Introduce preferred constructors (#9)

LICENSE

@@ -1,6 +1,6 @@
 MIT License
 
-Copyright (c) 2021 Macocian Alexandru Victor
+Copyright (c) 2022 Macocian Alexandru Victor
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

README.md

@@ -87,3 +87,5 @@ To retrieve all services of a certain type from the service manager, use
 serviceManager.GetServicesOfType<ISharedInterface>();
 ```
 This will return an `IEnumerable<ISharedInterface>` with all the services which implement the `ISharedInterface`.
+
+In order to give priority to certain constructors in a class, mark the constructors with `[PreferredConstructor]` attribute. `ServiceManager` will prioritize those constructors.

Slim.Tests/Models/ServiceWithPrefferedConstructor.cs

@@ -0,0 +1,19 @@
+using Slim.Attributes;
+
+namespace Slim.Tests.Models
+{
+    public sealed class ServiceWithPrefferedConstructor
+    {
+        public bool CalledPrefferedConstructor { get; init; }
+
+        public ServiceWithPrefferedConstructor()
+        {
+        }
+
+        [PrefferedConstructor]
+        public ServiceWithPrefferedConstructor(IIndependentService independentService)
+        {
+            this.CalledPrefferedConstructor = true;
+        }
+    }
+}

Slim.Tests/ServiceManagerTests.cs

@@ -727,5 +727,28 @@ namespace Slim.Tests
             dependentService1.Should().Be(dependentService2);
             dependentService1.IndependentService.Should().Be(dependentService2.IndependentService);
         }
+
+        [TestMethod]
+        public void ServiceWithPrefferedConstructorCallsPrefferedConstructor()
+        {
+            var di = new ServiceManager();
+            di.RegisterSingleton<IIndependentService, IndependentService>();
+            di.RegisterSingleton<ServiceWithPrefferedConstructor>();
+
+            var service = di.GetService<ServiceWithPrefferedConstructor>();
+
+            service.CalledPrefferedConstructor.Should().BeTrue();
+        }
+
+        [TestMethod]
+        public void ServiceWithPrefferedConstructorFallsBackToOtherConstructors()
+        {
+            var di = new ServiceManager();
+            di.RegisterSingleton<ServiceWithPrefferedConstructor>();
+
+            var service = di.GetService<ServiceWithPrefferedConstructor>();
+
+            service.CalledPrefferedConstructor.Should().BeFalse();
+        }
     }
 }

Slim/Attributes/PrefferedConstructorAttribute.cs

@@ -0,0 +1,18 @@
+using System;
+
+namespace Slim.Attributes
+{
+    /// <summary>
+    /// Attribute used to mark constructors to be used with priority by the <see cref="ServiceManager"/>.
+    /// </summary>
+    [AttributeUsage(AttributeTargets.Constructor)]
+    public sealed class PrefferedConstructorAttribute : Attribute
+    {
+        /// <summary>
+        /// Creates a new instance of <see cref="PrefferedConstructorAttribute"/>.
+        /// </summary>
+        public PrefferedConstructorAttribute()
+        {
+        }
+    }
+}

Slim/ServiceManager.cs

@@ -1,4 +1,5 @@
-using Slim.Exceptions;
+using Slim.Attributes;
+using Slim.Exceptions;
 using Slim.Resolvers;
 using System;
 using System.Collections.Generic;
@@ -682,7 +683,11 @@ namespace Slim
         }
         private object FindAndCallConstructors(Type implementType)
         {
-            var constructors = implementType.GetConstructors();
+            /*
+             * Order constructors to give priority to constructors that have PrefferedConstructorAttribute decorator
+             */
+            var constructors = implementType.GetConstructors()
+                .OrderBy(c => c.GetCustomAttribute<PrefferedConstructorAttribute>() is null);
             foreach (var constructor in constructors)
             {
                 /*

Slim/Slim.csproj

@@ -8,10 +8,10 @@
     <Company />
     <Product></Product>
     <Description>Service lifetime management and dependency injection framework.</Description>
-    <AssemblyVersion>1.7</AssemblyVersion>
-    <FileVersion>1.7</FileVersion>
+    <AssemblyVersion>1.7.1</AssemblyVersion>
+    <FileVersion>1.7.1</FileVersion>
     <PackageProjectUrl>https://github.com/AlexMacocian/Slim</PackageProjectUrl>
-    <Version>1.7</Version>
+    <Version>1.7.1</Version>
     <EnableNETAnalyzers>true</EnableNETAnalyzers>
     <PackageRequireLicenseAcceptance>true</PackageRequireLicenseAcceptance>
     <PackageLicenseFile>LICENSE</PackageLicenseFile>

Slim/Slim.xml

@@ -4,6 +4,16 @@
         <name>Slim</name>
     </assembly>
     <members>
+        <member name="T:Slim.Attributes.PrefferedConstructorAttribute">
+            <summary>
+            Attribute used to mark constructors to be used with priority by the <see cref="T:Slim.ServiceManager"/>.
+            </summary>
+        </member>
+        <member name="M:Slim.Attributes.PrefferedConstructorAttribute.#ctor">
+            <summary>
+            Creates a new instance of <see cref="T:Slim.Attributes.PrefferedConstructorAttribute"/>.
+            </summary>
+        </member>
         <member name="T:Slim.Exceptions.DependencyInjectionException">
             <summary>
             Exception thrown when <see cref="T:Slim.IServiceManager"/> fails to create a service.