From e34e562d892cfebc67407f7d3a0f9a725e1cd67a Mon Sep 17 00:00:00 2001
From: Oskar Dudycz <oskar.dudycz@gmail.com>
Date: Sat, 8 Oct 2022 10:23:06 +0200
Subject: [PATCH] Updated ObjectFactory implementation to use Expression with
 memoization to create new object instead of Activator.

---
 src/Ogooreck/Factories/ObjectFactory.cs | 55 +++++++++++--------------
 src/Ogooreck/Ogooreck.csproj            |  2 +-
 2 files changed, 25 insertions(+), 32 deletions(-)

diff --git a/src/Ogooreck/Factories/ObjectFactory.cs b/src/Ogooreck/Factories/ObjectFactory.cs
index 5344fce..d15e2bf 100644
--- a/src/Ogooreck/Factories/ObjectFactory.cs
+++ b/src/Ogooreck/Factories/ObjectFactory.cs
@@ -1,40 +1,33 @@
-using System.Runtime.CompilerServices;
+using System.Linq.Expressions;
+using System.Reflection;
+using System.Runtime.Serialization;
+
+#pragma warning disable CS1591
+
 namespace Ogooreck.Factories;
 
-/// <summary>
-/// Wraps objects creation
-/// </summary>
-/// <typeparam name="T"></typeparam>
 public static class ObjectFactory<T>
 {
-    /// <summary>
-    /// Creates empty unitialised instance of object T
-    /// </summary>
-    /// <returns></returns>
-    public static T GetUnitialized() =>
-        (T)RuntimeHelpers.GetUninitializedObject(typeof(T));
+    public static readonly Func<T> GetDefaultOrUninitialized = Creator();
 
-    /// <summary>
-    /// Creates empty unitialised instance of object T
-    /// </summary>
-    /// <returns></returns>
-    public static T? GetDefault()
+    private static Func<T> Creator()
     {
-        try
-        {
-            return (T?)Activator.CreateInstance(typeof(T), true);
-        }
-        catch (MissingMethodException? e)
-        {
-            Console.WriteLine(e);
-            return default;
-        }
+        var t = typeof(T);
+        if (t == typeof(string))
+            return Expression.Lambda<Func<T>>(Expression.Constant(string.Empty)).Compile();
+
+        if (t.HasDefaultConstructor())
+            return Expression.Lambda<Func<T>>(Expression.New(t)).Compile();
+
+        return () => (T)FormatterServices.GetUninitializedObject(t);
     }
+}
 
-    /// <summary>
-    /// Creates empty unitialised instance of object T
-    /// </summary>
-    /// <returns></returns>
-    public static T GetDefaultOrUninitialized()
-        => GetDefault() ?? GetUnitialized();
+public static class ObjectFactory
+{
+    public static bool HasDefaultConstructor(this Type t)
+    {
+        return t.IsValueType || t.GetConstructor(BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic,
+            null, Type.EmptyTypes, null) != null;
+    }
 }
diff --git a/src/Ogooreck/Ogooreck.csproj b/src/Ogooreck/Ogooreck.csproj
index aaba347..c884ce8 100644
--- a/src/Ogooreck/Ogooreck.csproj
+++ b/src/Ogooreck/Ogooreck.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
     <PropertyGroup>
-        <VersionPrefix>0.5.0</VersionPrefix>
+        <VersionPrefix>0.5.1</VersionPrefix>
         <TargetFramework>net6.0</TargetFramework>
         <GenerateAssemblyTitleAttribute>true</GenerateAssemblyTitleAttribute>
         <GenerateAssemblyDescriptionAttribute>true</GenerateAssemblyDescriptionAttribute>