Added a configuration method that allows binding non-public properties

Author: DevD4v3

src/Binder/EnvBinder.cs

@@ -45,7 +45,8 @@ public EnvBinder(IEnvironmentVariablesProvider provider)
             var settings = new TSettings();
             var type = typeof(TSettings);
             result = _validationResult;
-            foreach (PropertyInfo property in type.GetProperties())
+            var properties = _configuration.BindNonPublicProperties ? type.GetPublicAndNonPublicProperties() : type.GetProperties();
+            foreach (PropertyInfo property in properties)
             {
                 if(IsReadOnlyOrWriteOnly(property)) 
                     continue;
@@ -84,12 +85,19 @@ public EnvBinder(IEnvironmentVariablesProvider provider)
         /// <returns><c>true</c> if the property is read-only or write-only, or <c>false</c> if the property is read-write.</returns>
         private bool IsReadOnlyOrWriteOnly(PropertyInfo property)
             => !property.CanRead || !property.CanWrite;
-
+            
         /// <inheritdoc />
         public IEnvBinder IgnoreException()
         {
             _configuration.ThrowException = false;
             return this;
         }
+
+        /// <inheritdoc />
+        public IEnvBinder AllowBindNonPublicProperties()
+        {
+            _configuration.BindNonPublicProperties = true;
+            return this;
+        }
     }
 }

src/Binder/EnvBinderOptions.cs

@@ -13,6 +13,12 @@ internal class EnvBinderOptions
         /// </summary>
         public bool ThrowException { get; set; } = true;
 
+        /// <summary>
+        /// When <c>false</c> (the default), the binder will only to set public properties. 
+        /// If <c>true</c>, the binder will to set all non-public properties.
+        /// </summary>
+        public bool BindNonPublicProperties { get; set; }
+
         /// <summary>
         /// Gets or sets the environment variables provider.
         /// </summary>

src/Binder/IEnvBinder.cs

@@ -13,12 +13,13 @@ public interface IEnvBinder
         TSettings Bind<TSettings>(out EnvValidationResult result) where TSettings : new();
 
         /// <summary>
-        /// Binds the instance of the environment variables provider to a new instance of type TSettings (binds only read-write properties).
+        /// Binds the instance of the environment variables provider to a new instance of type TSettings.
         /// </summary>
         /// <typeparam name="TSettings">The type of the new instance to bind.</typeparam>
         /// <exception cref="BinderException">
         /// If the binder encounters one or more errors.
         /// </exception>
+        /// <remarks>Binds only read-write properties and, moreover, only sets public properties.</remarks>
         /// <returns>The new instance of TSettings.</returns>
         TSettings Bind<TSettings>() where TSettings : new();
 
@@ -27,5 +28,12 @@ public interface IEnvBinder
         /// </summary>
         /// <returns>An instance implementing the fluent interface.</returns>
         IEnvBinder IgnoreException();
+
+        /// <summary>
+        /// Allows binding of non-public properties.
+        /// This method tells the binder that it can set non-public properties.
+        /// </summary>
+        /// <returns>An instance implementing the fluent interface.</returns>
+        IEnvBinder AllowBindNonPublicProperties();
     }
 }

src/Extensions/TypeExtensions.cs

@@ -0,0 +1,19 @@
+using System;
+using System.Collections.Generic;
+using System.Reflection;
+
+namespace DotEnv.Core
+{
+    internal static class TypeExtensions
+    {
+        /// <summary>
+        /// Returns all public and non-public properties.
+        /// </summary>
+        /// <param name="type"></param>
+        /// <returns>
+        /// An array of <see cref="PropertyInfo" /> objects representing all public and non-public properties of the current <see cref="Type" />.
+        /// </returns>
+        public static PropertyInfo[] GetPublicAndNonPublicProperties(this Type type)
+            => type.GetProperties(BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance);
+    }
+}