Fixes #4, renames ServiceLifetime.Lifetime to Singleton, adds support for arguments in constructors, version bumps.

DISandbox/Program.cs

@@ -49,6 +49,16 @@ class GuidDependantService {
     }
 }
 
+public interface ICacheService {
+    public Uri CacheLocation { get; set; }
+}
+
+public class CacheService : ICacheService {
+    public required Uri CacheLocation { get; set; }
+    public CacheService() => CacheLocation = new Uri("http://default.cache");
+    public CacheService(Uri cacheLocation) => CacheLocation = cacheLocation;
+}
+
 static class Program {
     static void Main(string[] args) {
         var container = new ServiceContainer()
@@ -63,5 +73,12 @@ static class Program {
         container.GetService<GuidDependantService>().LogWithId("Hello, sent from the dependency.");
         container.GetService<IService>().Log("Goodbye, Dependency Injection!");
         var res = container.GetServices<IService>();
+        
+        var testContainer = new ServiceContainer()
+            .AddSingleton<ICacheService, CacheService>(new Uri("http://cache.local"));
+        var iCacheService = testContainer.GetService<ICacheService>();
+        Console.WriteLine($"[ICacheService] {iCacheService.CacheLocation}");
+        var cacheService = testContainer.GetService<CacheService>();
+        Console.WriteLine($"[CacheService] {cacheService.CacheLocation}");
     }
 }

Syrette/ServiceContainer.cs

@@ -37,7 +37,25 @@ public class ServiceContainer {
         descriptors.Add(new() {
             ServiceType = typeof(TInterface),
             ImplementationType = typeof(TImplementation),
-            Lifetime = ServiceLifetime.Lifetime
+            Lifetime = ServiceLifetime.Singleton
+        });
+        return this;
+    }
+
+    /// <summary>
+    /// Registers a singleton service with its implementation.
+    /// </summary>
+    /// <param name="args">Arguments to be passed to the constructor, in order of appearance if of the same type.</param>
+    /// <typeparam name="TInterface">Interface the service is implementing</typeparam>
+    /// <typeparam name="TImplementation">Implementation type of the service</typeparam>
+    public ServiceContainer AddSingleton<TInterface, TImplementation>(params object[] args)
+        where TInterface : class
+        where TImplementation : class, TInterface {
+        descriptors.Add(new() {
+            ServiceType = typeof(TInterface),
+            ImplementationType = typeof(TImplementation),
+            Lifetime = ServiceLifetime.Singleton,
+            Arguments = args.ToList()
         });
         return this;
     }
@@ -51,7 +69,23 @@ public class ServiceContainer {
         descriptors.Add(new() {
             ServiceType = typeof(TClass),
             ImplementationType = typeof(TClass),
-            Lifetime = ServiceLifetime.Lifetime
+            Lifetime = ServiceLifetime.Singleton
+        });
+        return this;
+    }
+
+    /// <summary>
+    /// Registers a singleton service with its implementation.
+    /// </summary>
+    /// <param name="args">Arguments to be passed to the constructor, in order of appearance if of the same type.</param>
+    /// <typeparam name="TImplementation">Implementation type of the service</typeparam>
+    public ServiceContainer AddSingleton<TImplementation>(params object[] args)
+        where TImplementation : class {
+        descriptors.Add(new() {
+            ServiceType = typeof(TImplementation),
+            ImplementationType = typeof(TImplementation),
+            Lifetime = ServiceLifetime.Singleton,
+            Arguments = args.ToList()
         });
         return this;
     }
@@ -72,6 +106,24 @@ public class ServiceContainer {
         return this;
     }
 
+    /// <summary>
+    /// Registers a transient service with its implementation.
+    /// </summary>
+    /// <param name="args">Arguments to be passed to the constructor, in order of appearance if of the same type.</param>
+    /// <typeparam name="TInterface">Interface the service is implementing</typeparam>
+    /// <typeparam name="TImplementation">Implementation type of the service</typeparam>
+    public ServiceContainer AddTransient<TInterface, TImplementation>(params object[] args)
+        where TInterface : class
+        where TImplementation : class, TInterface {
+        descriptors.Add(new() {
+            ServiceType = typeof(TInterface),
+            ImplementationType = typeof(TImplementation),
+            Lifetime = ServiceLifetime.Transient,
+            Arguments = args.ToList()
+        });
+        return this;
+    }
+
     /// <summary>
     /// Registers a transient service where the service type is the same as the implementation type.
     /// </summary>
@@ -86,6 +138,22 @@ public class ServiceContainer {
         return this;
     }
 
+    /// <summary>
+    /// Registers a transient service where the service type is the same as the implementation type.
+    /// </summary>
+    /// <param name="args">Arguments to be passed to the constructor, in order of appearance if of the same type.</param>
+    /// <typeparam name="TClass">Class type of the service</typeparam>
+    public ServiceContainer AddTransient<TClass>(params object[] args)
+        where TClass : class {
+        descriptors.Add(new() {
+            ServiceType = typeof(TClass),
+            ImplementationType = typeof(TClass),
+            Lifetime = ServiceLifetime.Transient,
+            Arguments = args.ToList()
+        });
+        return this;
+    }
+
     // you can't call generic methods with an unknown type at compile time
     // so we use reflection to call the generic GetService<T> method with the provided type
     // Basically we build the method GetService<serviceType>() at runtime and then call it.
@@ -97,6 +165,17 @@ public class ServiceContainer {
         return method.Invoke(this, null)!;
     }
     
+    private object? TryGetService(Type serviceType) {
+        var method = typeof(ServiceContainer)
+            .GetMethod(nameof(GetService))!
+            .MakeGenericMethod(serviceType);
+        try {
+            return method.Invoke(this, null)!;
+        } catch {
+            return null!;
+        }
+    }
+
     /// <summary>
     /// Resolves and returns an instance of the requested service type.
     /// </summary>
@@ -108,25 +187,31 @@ public class ServiceContainer {
         if (descriptor == null) throw new Exception($"Service of type {typeof(TService)} not registered.");
 
         var ctors = descriptor.ImplementationType.GetConstructors();
+        var par = descriptor.Arguments ?? new List<object>();
         int max = -1;
         ConstructorInfo? bestCtor = null;
 
         foreach (var ctor in ctors) {
             var parameters = ctor.GetParameters();
-            //check if all parameters are registered services or optional
-            if (!parameters.All(p => descriptors.Any(d => d.ServiceType == p.ParameterType) || p.IsOptional)) continue;
+            //check if all parameters are registered services or optional or have been provided as arguments
+            if (parameters.Any(p => descriptors.All(d => d.ServiceType != p.ParameterType) && par.All(a => a.GetType() != p.ParameterType) && !p.IsOptional))
+                continue;
+
             //check if this constructor has more registered parameters than the previous best
             int satisfiedParams = parameters.Count(p => descriptors.Any(d => d.ServiceType == p.ParameterType));
+            satisfiedParams += par.Count(arg => parameters.Any(p => p.ParameterType == arg.GetType()));
+
             if (satisfiedParams > max) {
                 max = satisfiedParams;
                 bestCtor = ctor;
             }
         }
+
         if (bestCtor == null)
             throw new Exception($"Cannot create service of type {typeof(TService)}. No suitable constructor found.");
 
         // Transient: create a new instance each time
-        if (descriptor.Lifetime != ServiceLifetime.Lifetime) {
+        if (descriptor.Lifetime != ServiceLifetime.Singleton) {
             var service = Instantiate<TService>(descriptor, bestCtor);
             return service;
         }
@@ -135,7 +220,7 @@ public class ServiceContainer {
         if (singletons.TryGetValue(descriptor.ServiceType, out object? singleton)) return (TService)singleton;
 
         // or create a new one if not yet created.
-        var newSingleton = Instantiate<TService>(descriptor);
+        var newSingleton = Instantiate<TService>(descriptor, bestCtor);
         singletons[descriptor.ServiceType] = newSingleton!;
         return newSingleton;
     }
@@ -144,23 +229,44 @@ public class ServiceContainer {
         if (ctor == null && descriptor.ImplementationType.GetConstructors().Length > 1)
             throw new Exception($"Multiple constructors found for type {descriptor.ImplementationType}. Please provide a specific constructor.");
 
-        List<Type> par;
+        List<ParameterInfo> par;
+        List<object> args = descriptor.Arguments ?? new List<object>();
 
         if (ctor == null)
             par = descriptor.ImplementationType
                 .GetConstructors().Single()
                 .GetParameters()
-                .Select(p => p.ParameterType)
+                //.Select(p => p.ParameterType)
                 .ToList();
         else
             par = ctor.GetParameters()
-                .Select(p => p.ParameterType)
+                //.Select(p => p.ParameterType)
                 .ToList();
 
         object[] parameters = new object[par.Count];
 
-        for (int i = 0; i < par.Count; i++)
-            parameters[i] = GetService(par[i]);
+        for (int i = 0; i < par.Count; i++) {
+            object? arg = args.FirstOrDefault(a => a.GetType() == par[i].ParameterType);
+            if (arg != null) { // this parameter is satisfied by a provided argument
+                parameters[i] = arg;
+                args.Remove(arg); // remove to handle multiple parameters of the same type
+                continue;
+            }
+            
+            arg = TryGetService(par[i].ParameterType);
+            if (arg != null) {
+                // this parameter is satisfied by a registered service
+                parameters[i] = arg;
+                continue;
+            }
+            
+            if (par[i].IsOptional) {
+                // this parameter is optional and not provided, use default value
+                parameters[i] = par[i].DefaultValue!;
+                continue;
+            }
+            throw new Exception($"Cannot resolve parameter {par[i].Name} of type {par[i].ParameterType} for service {descriptor.ImplementationType}");
+        }
 
         var service = (TInterface?)Activator.CreateInstance(descriptor.ImplementationType, parameters);
 

Syrette/ServiceDescriptor.cs

@@ -19,4 +19,9 @@ public class ServiceDescriptor
     /// Gets or sets the lifetime of the service (e.g., Singleton or Transient).
     /// </summary>
     public required ServiceLifetime Lifetime { get; set; }
+    
+    /// <summary>
+    /// Arguments to be passed to the constructor of the implementation type.
+    /// </summary>
+    public List<object>? Arguments { get; set; }
 }

Syrette/ServiceLifetime.cs

@@ -7,7 +7,7 @@ public enum ServiceLifetime {
     /// <summary>
     /// Defines a singleton service, which is created once and shared throughout the application's lifetime.
     /// </summary>
-    Lifetime,
+    Singleton,
     /// <summary>
     /// Defines a transient service, which is created anew each time it is requested.
     /// </summary>

Syrette/Syrette.csproj

@@ -9,7 +9,7 @@
         <LangVersion>latest</LangVersion>
         <ImplicitUsings>enable</ImplicitUsings>
         <Nullable>enable</Nullable>
-        <Version>0.0.1.5-alpha</Version>
+        <Version>0.0.1.6-alpha</Version>
         <Title>Syrette </Title>
         <Authors>Lorefice Samuele</Authors>
         <Description>Syrette is a minimalistic dependency injection library for C#. It aims to provide a simple and efficient way to achieve dependency injections in your applications without the overhead of larger frameworks.</Description>