✨Create generic version of converter attributes (#171)

fixes #150 
(MINOR)

Author: mgrosperrin

docs/class-based/customize-class-based-option.md

@@ -11,3 +11,6 @@ You can customize the behavior of the options with some annotations (the parser
   - `Name` and `ShortName` to respectively change the long and short form of the option
   - `Description` to define a description in the auto-generated help for the option,
 - Use any of the `System.ComponentModel.DataAnnotations.ValidationAttribute` derived class to validate the value provided for the option.
+
+If the type of your option is not covered by one of the [built-in converters](../extensibility/built-in-converters.md),
+you can create and register [your own](../extensibility/converter.md).

src/MGR.CommandLineParser/Command/ConverterAttribute.cs

@@ -4,9 +4,10 @@
 namespace MGR.CommandLineParser.Command
 {
     /// <summary>
-    /// Defines the converter type for a dictionary property.
+    /// Defines the converter type for a property.
     /// </summary>
     [AttributeUsage(AttributeTargets.Property)]
+    [Obsolete("Use the generic version of the MGR.CommandLineParser.Command.ConverterAttribute if you use C#11+. This attribute will be removed in a future version.")]
     public sealed class ConverterAttribute : Attribute
     {
         /// <summary>

src/MGR.CommandLineParser/Command/ConverterAttribute`1.cs

@@ -0,0 +1,12 @@
+using System;
+using MGR.CommandLineParser.Extensibility.Converters;
+
+namespace MGR.CommandLineParser.Command;
+
+/// <summary>
+/// Defines the converter type for a property.
+/// </summary>
+[AttributeUsage(AttributeTargets.Property)]
+public sealed class ConverterAttribute<TConverter> : Attribute
+    where TConverter : IConverter
+{ }

src/MGR.CommandLineParser/Command/ConverterKeyValueAttribute.cs

@@ -7,6 +7,7 @@ namespace MGR.CommandLineParser.Command
     /// Defines the key and the value converter types for a dictionary property.
     /// </summary>
     [AttributeUsage(AttributeTargets.Property)]
+    [Obsolete("Use the generic version of the MGR.CommandLineParser.Command.ConverterKeyValueAttribute if you use C#11+. This attribute will be removed in a future version.")]
     public sealed class ConverterKeyValueAttribute : Attribute
     {
         /// <summary>

src/MGR.CommandLineParser/Command/ConverterKeyValueAttribute`1.cs

@@ -0,0 +1,12 @@
+using System;
+using MGR.CommandLineParser.Extensibility.Converters;
+
+namespace MGR.CommandLineParser.Command;
+
+/// <summary>
+/// Defines the converter type for a dictionary property.
+/// </summary>
+[AttributeUsage(AttributeTargets.Property)]
+public sealed class ConverterKeyValueAttribute<TKeyConverter> : ConverterKeyValueAttribute<TKeyConverter, StringConverter>
+    where TKeyConverter : IConverter
+{ }

src/MGR.CommandLineParser/Command/ConverterKeyValueAttribute`2.cs

@@ -0,0 +1,13 @@
+using System;
+using MGR.CommandLineParser.Extensibility.Converters;
+
+namespace MGR.CommandLineParser.Command;
+
+/// <summary>
+/// Defines the key and the value converter types for a dictionary property.
+/// </summary>
+[AttributeUsage(AttributeTargets.Property)]
+public class ConverterKeyValueAttribute<TKeyConverter, TValueConverter> : Attribute
+    where TKeyConverter : IConverter
+    where TValueConverter : IConverter
+{ }

src/MGR.CommandLineParser/Extensions/ConverterAttributeExtensions.cs

@@ -6,19 +6,25 @@ namespace MGR.CommandLineParser.Command
 {
     internal static class ConverterAttributeExtensions
     {
+#pragma warning disable CS0618 // Type or member is obsolete
         internal static IConverter BuildConverter(this ConverterAttribute source)
+#pragma warning restore CS0618 // Type or member is obsolete
         {
             Guard.NotNull(source, nameof(source));
 
             return Activator.CreateInstance(source.ConverterType) as IConverter;
         }
+#pragma warning disable CS0618 // Type or member is obsolete
         internal static IConverter BuildKeyConverter(this ConverterKeyValueAttribute source)
+#pragma warning restore CS0618 // Type or member is obsolete
         {
             Guard.NotNull(source, nameof(source));
 
             return Activator.CreateInstance(source.KeyConverterType) as IConverter;
         }
+#pragma warning disable CS0618 // Type or member is obsolete
         internal static IConverter BuildValueConverter(this ConverterKeyValueAttribute source)
+#pragma warning restore CS0618 // Type or member is obsolete
         {
             Guard.NotNull(source, nameof(source));
 

src/MGR.CommandLineParser/Extensions/PropertyInfoExtensions.cs

@@ -70,7 +70,21 @@ private static IConverter FindKeyConverter(PropertyInfo propertyInfo, IEnumerabl
 
         private static IConverter GetConverterFromAttribute(PropertyInfo propertyInfo, string commandName)
         {
+            var genericConverterAttribute = propertyInfo.GetCustomAttributes(typeof(ConverterAttribute<>), true).FirstOrDefault();
+            if (genericConverterAttribute != null)
+            {
+                var converterType = genericConverterAttribute.GetType().GetGenericArguments()[0];
+                var converter = Activator.CreateInstance(converterType) as IConverter;
+
+                if (!converter.CanConvertTo(propertyInfo.PropertyType))
+                {
+                    throw new CommandLineParserException(Constants.ExceptionMessages.ParserSpecifiedConverterNotValid(propertyInfo.Name, commandName, propertyInfo.PropertyType, converter.TargetType));
+                }
+                return converter;
+            }
+#pragma warning disable CS0618 // Type or member is obsolete
             var converterAttribute = propertyInfo.GetCustomAttributes(typeof(ConverterAttribute), true).FirstOrDefault() as ConverterAttribute;
+#pragma warning restore CS0618 // Type or member is obsolete
             if (converterAttribute != null)
             {
                 var converter = converterAttribute.BuildConverter();
@@ -86,7 +100,24 @@ private static IConverter GetConverterFromAttribute(PropertyInfo propertyInfo, s
 
         private static IConverter GetKeyValueConverterFromAttribute(PropertyInfo propertyInfo, string optionName, string commandName)
         {
+            var genericConverterKeyValuePairAttribute = propertyInfo.GetCustomAttributes(typeof(ConverterKeyValueAttribute<,>), true).FirstOrDefault();
+            if (genericConverterKeyValuePairAttribute != null)
+            {
+                if (!propertyInfo.PropertyType.IsDictionaryType())
+                {
+                    throw new CommandLineParserException(Constants.ExceptionMessages.ParserExtractConverterKeyValueConverterIsForIDictionaryProperty(optionName, commandName));
+                }
+                var genericArguments = genericConverterKeyValuePairAttribute.GetType().GetGenericArguments();
+                var keyConverterType = genericArguments[0];
+                var keyConverter = Activator.CreateInstance(keyConverterType) as IConverter;
+                var valueConverterType = genericArguments.Length == 1 ? typeof(MGR.CommandLineParser.Extensibility.Converters.StringConverter) : genericConverterKeyValuePairAttribute.GetType().GetGenericArguments()[1];
+                var valueConverter = Activator.CreateInstance(valueConverterType) as IConverter;
+
+                return new KeyValueConverter(keyConverter, valueConverter);
+            }
+#pragma warning disable CS0618 // Type or member is obsolete
             var converterKeyValuePairAttribute = propertyInfo.GetCustomAttributes(typeof(ConverterKeyValueAttribute), true).FirstOrDefault() as ConverterKeyValueAttribute;
+#pragma warning restore CS0618 // Type or member is obsolete
             if (converterKeyValuePairAttribute != null)
             {
                 if (!propertyInfo.PropertyType.IsDictionaryType())
@@ -101,7 +132,9 @@ private static IConverter GetKeyValueConverterFromAttribute(PropertyInfo propert
             return null;
         }
 
+#pragma warning disable CS0618 // Type or member is obsolete
         private static IConverter GetValueConverter(PropertyInfo propertyInfo, string optionName, string commandName, ConverterKeyValueAttribute converterKeyValuePairAttribute)
+#pragma warning restore CS0618 // Type or member is obsolete
         {
             var valueType = propertyInfo.PropertyType.GetUnderlyingDictionaryType(false);
             var valueConverter = converterKeyValuePairAttribute.BuildValueConverter();
@@ -112,7 +145,9 @@ private static IConverter GetValueConverter(PropertyInfo propertyInfo, string op
             return valueConverter;
         }
 
+#pragma warning disable CS0618 // Type or member is obsolete
         private static IConverter GetKeyConverter(PropertyInfo propertyInfo, string optionName, string commandName, ConverterKeyValueAttribute converterKeyValuePairAttribute)
+#pragma warning restore CS0618 // Type or member is obsolete
         {
             var keyType = propertyInfo.PropertyType.GetUnderlyingDictionaryType(true);
             var keyConverter = converterKeyValuePairAttribute.BuildKeyConverter();

tests/MGR.CommandLineParser.IntegrationTests/Help/AsOptionsTests.cs

@@ -1,5 +1,4 @@
 using System.Collections.Generic;
-using System.Linq;
 using System.Threading.Tasks;
 using MGR.CommandLineParser.Extensibility.ClassBased;
 using MGR.CommandLineParser.Tests.Commands;

tests/MGR.CommandLineParser.UnitTests/Extensibility/ClassBased/ClassBasedCommandTypeTests.CreateCommand.cs

@@ -43,7 +43,9 @@ public void PropertyWithNoConverterException()
             }
             private class TestBadConverterCommand : ICommand
             {
+#pragma warning disable CS0618 // Type or member is obsolete
                 [Converter(typeof(BooleanConverter))]
+#pragma warning restore CS0618 // Type or member is obsolete
                 // ReSharper disable once UnusedMember.Local
                 // ReSharper disable once UnusedAutoPropertyAccessor.Local
                 public int PropertySimpleWithBadConverter { get; set; }