Add command description

CliFx.Tests.Dummy/Commands/AddCommand.cs

@@ -7,10 +7,10 @@ using CliFx.Models;
 
 namespace CliFx.Tests.Dummy.Commands
 {
-    [Command("add")]
+    [Command("add", Description = "Calculate the sum of all input values.")]
     public class AddCommand : Command
     {
-        [CommandOption("values", 'v', IsRequired = true, Description = "Values.")]
+        [CommandOption("values", 'v', IsRequired = true, Description = "Input values.")]
         public IReadOnlyList<double> Values { get; set; }
 
         public override ExitCode Execute()

CliFx.Tests.Dummy/Commands/LogCommand.cs

@@ -2,10 +2,11 @@
 using System.Globalization;
 using CliFx.Attributes;
 using CliFx.Models;
+using CliFx.Services;
 
 namespace CliFx.Tests.Dummy.Commands
 {
-    [Command("log")]
+    [Command("log", Description = "Calculate the logarithm of a value.")]
     public class LogCommand : Command
     {
         [CommandOption("value", 'v', IsRequired = true, Description = "Value whose logarithm is to be found.")]

CliFx/Attributes/CommandAttribute.cs

@@ -7,6 +7,8 @@ namespace CliFx.Attributes
     {
         public string Name { get; }
 
+        public string Description { get; set; }
+
         public CommandAttribute(string name)
         {
             Name = name;

CliFx/Attributes/DefaultCommandAttribute.cs

@@ -3,7 +3,11 @@
 namespace CliFx.Attributes
 {
     [AttributeUsage(AttributeTargets.Class, Inherited = false)]
-    public class DefaultCommandAttribute : Attribute
+    public class DefaultCommandAttribute : CommandAttribute
     {
+        public DefaultCommandAttribute()
+            : base(null)
+        {
+        }
     }
 }

CliFx/Internal/CommandType.cs

@@ -14,17 +14,19 @@ namespace CliFx.Internal
 
         public bool IsDefault { get; }
 
-        public CommandType(Type type, string name, bool isDefault)
+        public string Description { get; }
+
+        public IReadOnlyList<CommandOptionProperty> Options { get; }
+
+        public CommandType(Type type, string name, bool isDefault, string description, IReadOnlyList<CommandOptionProperty> options)
         {
             _type = type;
             Name = name;
             IsDefault = isDefault;
+            Description = description;
+            Options = options;
         }
 
-        public IEnumerable<CommandOptionProperty> GetOptionProperties() => _type.GetProperties()
-            .Where(CommandOptionProperty.IsValid)
-            .Select(CommandOptionProperty.Initialize);
-
         public Command Activate() => (Command) Activator.CreateInstance(_type);
     }
 
@@ -41,10 +43,18 @@ namespace CliFx.Internal
             if (!IsValid(type))
                 throw new InvalidOperationException($"[{type.Name}] is not a valid command type.");
 
-            var name = type.GetCustomAttribute<CommandAttribute>()?.Name;
-            var isDefault = type.IsDefined(typeof(DefaultCommandAttribute));
+            var attribute = type.GetCustomAttribute<CommandAttribute>();
 
-            return new CommandType(type, name, isDefault);
+            var name = attribute.Name;
+            var isDefault = attribute is DefaultCommandAttribute;
+            var description = attribute.Description;
+
+            var options = type.GetProperties()
+                .Where(CommandOptionProperty.IsValid)
+                .Select(CommandOptionProperty.Initialize)
+                .ToArray();
+
+            return new CommandType(type, name, isDefault, description, options);
         }
 
         public static IEnumerable<CommandType> GetCommandTypes(IEnumerable<Type> types) => types.Where(IsValid).Select(Initialize);

CliFx/Services/CommandResolver.cs

@@ -84,7 +84,7 @@ namespace CliFx.Services
             var command = commandType.Activate();
 
             // Set command options
-            foreach (var property in commandType.GetOptionProperties())
+            foreach (var property in commandType.Options)
             {
                 // Get option for this property
                 var option = optionSet.GetOptionOrDefault(property.Name, property.ShortName);
@@ -95,7 +95,7 @@ namespace CliFx.Services
                     var convertedValue = _commandOptionConverter.ConvertOption(option, property.Type);
                     property.SetValue(command, convertedValue);
                 }
-                // If the property is missing but it's required - throw
+                // If the property is required but it's missing - throw
                 else if (property.IsRequired)
                 {
                     throw new CommandResolveException($"Can't resolve command because required property [{property.Name}] is not set.");