Changes to Logging API

Author: BrennanConroy

src/Microsoft.Extensions.Logging.Abstractions/EventId.cs

@@ -0,0 +1,38 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+namespace Microsoft.Extensions.Logging
+{
+    public struct EventId
+    {
+        private int _id;
+        private string _name;
+
+        public EventId(int id, string name = null)
+        {
+            _id = id;
+            _name = name;
+        }
+
+        public int Id
+        {
+            get
+            {
+                return _id;
+            }
+        }
+
+        public string Name
+        {
+            get
+            {
+                return _name;
+            }
+        }
+
+        public static implicit operator EventId(int i)
+        {
+            return new EventId(i);
+        }
+    }
+}

src/Microsoft.Extensions.Logging.Abstractions/ILogValues.cs

@@ -19,7 +19,7 @@ public interface ILogger
         /// <param name="exception"></param>
         /// <param name="formatter"></param>
         /// <returns></returns>
-        void Log(LogLevel logLevel, int eventId, object state, Exception exception, Func<object, Exception, string> formatter);
+        void Log<TState>(LogLevel logLevel, EventId eventId, TState state, Exception exception, Func<TState, Exception, string> formatter);
 
         /// <summary>
         /// Checks if the given LogLevel is enabled.

src/Microsoft.Extensions.Logging.Abstractions/ILogger.cs

@@ -1,6 +1,8 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
+using System;
+using System.Collections;
 using System.Collections.Concurrent;
 using System.Collections.Generic;
 
@@ -10,26 +12,58 @@ namespace Microsoft.Extensions.Logging.Internal
     /// LogValues to enable formatting options supported by <see cref="string.Format"/>. 
     /// This also enables using {NamedformatItem} in the format string.
     /// </summary>
-    public class FormattedLogValues : ILogValues
+    public class FormattedLogValues : IReadOnlyList<KeyValuePair<string, object>>
     {
         private static ConcurrentDictionary<string, LogValuesFormatter> _formatters = new ConcurrentDictionary<string, LogValuesFormatter>();
         private readonly LogValuesFormatter _formatter;
         private readonly object[] _values;
 
         public FormattedLogValues(string format, params object[] values)
         {
+            if (format == null)
+            {
+                throw new ArgumentNullException(nameof(format));
+            }
             _formatter = _formatters.GetOrAdd(format, f => new LogValuesFormatter(f));
             _values = values;
         }
 
-        public IEnumerable<KeyValuePair<string, object>> GetValues()
+        public KeyValuePair<string, object> this[int index]
         {
-            return _formatter.GetValues(_values);
+            get
+            {
+                if (index > Count)
+                {
+                    throw new IndexOutOfRangeException(nameof(index));
+                }
+                return _formatter.GetValue(_values, index);
+            }
+        }
+
+        public int Count
+        {
+            get
+            {
+                return _formatter.ValueNames.Count + 1;
+            }
+        }
+
+        public IEnumerator<KeyValuePair<string, object>> GetEnumerator()
+        {
+            for (int i = 0; i < Count; ++i)
+            {
+                yield return this[i];
+            }
         }
 
         public override string ToString()
         {
             return _formatter.Format(_values);
         }
+
+        IEnumerator IEnumerable.GetEnumerator()
+        {
+            return GetEnumerator();
+        }
     }
 }

src/Microsoft.Extensions.Logging.Abstractions/Internal/FormattedLogValues.cs

@@ -1,6 +1,7 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
+using System;
 using System.Collections;
 using System.Collections.Generic;
 using System.Linq;
@@ -144,6 +145,21 @@ public string Format(object[] values)
             return string.Format(CultureInfo.InvariantCulture, _format, values);
         }
 
+        public KeyValuePair<string, object> GetValue(object[] values, int index)
+        {
+            if (index < 0 || index > _valueNames.Count + 1)
+            {
+                throw new IndexOutOfRangeException(nameof(index));
+            }
+
+            if (_valueNames.Count > index)
+            {
+                return new KeyValuePair<string, object>(_valueNames[index], values[index]);
+            }
+
+            return new KeyValuePair<string, object>("{OriginalFormat}", OriginalFormat);
+        }
+
         public IEnumerable<KeyValuePair<string, object>> GetValues(object[] values)
         {
             var valueArray = new KeyValuePair<string, object>[values.Length + 1];