Allow Suggestions to be replaced

src/System.CommandLine.Benchmarks/CommandLine/Perf_Parser_Directives_Suggest.cs

@@ -29,12 +29,16 @@ public void Setup()
                 new Option("--fruit")
                 {
                     Argument = new Argument<string>()
-                        .WithSuggestions("apple", "banana", "cherry")
+                    {
+                        Suggestions = {"apple", "banana", "cherry" }
+                    }
                 },
                 new Option("--vegetable")
                 {
                     Argument = new Argument<string>()
-                        .WithSuggestions("asparagus", "broccoli", "carrot")
+                    {
+                        Suggestions = {"asparagus", "broccoli", "carrot" }
+                    }
                 }
             };
 

src/System.CommandLine.Benchmarks/CommandLine/Perf_Suggestions.cs

@@ -41,9 +41,9 @@ public void Setup_FromSymbol()
             {
                 Argument = new Argument
                     {
-                        Arity = ArgumentArity.ExactlyOne
-                    }
-                    .WithSuggestions(GenerateSuggestionsArray(TestSuggestionsCount))
+                        Arity = ArgumentArity.ExactlyOne,
+                        Suggestions = { GenerateSuggestionsArray(TestSuggestionsCount) }
+                }
             };
         }
 

src/System.CommandLine.Tests/ApprovalTests/Help/HelpBuilderTests.Approval.cs

@@ -61,7 +61,7 @@ public void Help_describes_default_values_for_complex_root_command_scenario()
                     Argument = new Argument<FileAccess>("the-root-option-arg", () => FileAccess.Read)
                     {
                         Description = "the-root-option-arg-description",
-                    },
+                    }
                 },
                 new Option(aliases: new string[] {"--the-root-option-required-enum-arg", "-trorea"}) {
                     Description = "the-root-option-description",

src/System.CommandLine.Tests/SuggestDirectiveTests.cs

@@ -2,7 +2,6 @@
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
 
 using System.CommandLine.Builder;
-using System.CommandLine.Invocation;
 using System.CommandLine.IO;
 using System.CommandLine.Parsing;
 using System.Threading.Tasks;
@@ -23,10 +22,10 @@ public class SuggestDirectiveTests
         public SuggestDirectiveTests()
         {
             _fruitOption = new Option<string>("--fruit")
-                .WithSuggestions("apple", "banana", "cherry");
+                .AddSuggestions("apple", "banana", "cherry");
 
             _vegetableOption = new Option<string>("--vegetable")
-                .WithSuggestions("asparagus", "broccoli", "carrot");
+                .AddSuggestions("asparagus", "broccoli", "carrot");
 
             _eatCommand = new Command("eat")
             {

src/System.CommandLine.Tests/SuggestionTests.cs

@@ -29,9 +29,9 @@ public void Option_Suggest_returns_argument_suggestions_if_configured()
             {
                 Argument = new Argument
                     {
-                        Arity = ArgumentArity.ExactlyOne
+                        Arity = ArgumentArity.ExactlyOne,
+                        Suggestions = { "one", "two", "three" }
                     }
-                    .WithSuggestions("one", "two", "three")
             };
 
             var suggestions = option.GetSuggestions();
@@ -102,9 +102,9 @@ public void Command_Suggest_returns_available_subcommands_and_option_aliases_and
                 new Option("--option", "option"),
                 new Argument
                     {
-                        Arity = ArgumentArity.OneOrMore
+                        Arity = ArgumentArity.OneOrMore,
+                        Suggestions = { "command-argument" }
                     }
-                    .WithSuggestions("command-argument")
             };
 
             var suggestions = command.GetSuggestions();
@@ -505,9 +505,9 @@ public void Suggestions_can_be_provided_in_the_absence_of_validation()
                     {
                         Argument = new Argument
                             {
-                                Arity = ArgumentArity.ExactlyOne
+                                Arity = ArgumentArity.ExactlyOne,
+                                Suggestions = { "vegetable", "mineral", "animal" }
                             }
-                            .WithSuggestions("vegetable", "mineral", "animal")
                     }
                 };
 
@@ -529,14 +529,9 @@ public void Command_argument_suggestions_can_be_provided_using_a_delegate()
                 {
                     new Argument
                         {
-                            Arity = ArgumentArity.ExactlyOne
+                            Arity = ArgumentArity.ExactlyOne,
+                            Suggestions = { _ => new[] { "vegetable", "mineral", "animal" } }
                         }
-                        .WithSuggestionSource(_ => new[]
-                        {
-                            "vegetable",
-                            "mineral",
-                            "animal"
-                        })
                 }
             };
 
@@ -551,13 +546,13 @@ public void Option_argument_suggestions_can_be_provided_using_a_delegate()
         {
             var command = new Command("the-command")
             {
-                new Option<string>("-x")
-                    .WithSuggestionSource(_ => new[]
+                new Option<string>("-x") 
+                {
+                    Argument = new Argument<string>()
                     {
-                        "vegetable",
-                        "mineral",
-                        "animal"
-                    })
+                        Suggestions = { _ => new[] { "vegetable", "mineral", "animal" } }
+                    }
+                }
             };
 
             var parseResult = command.Parse("the-command -x m");
@@ -997,6 +992,49 @@ public void When_there_are_multiple_arguments_then_suggestions_are_only_offered_
             {
                 Assert.True(false, "Test testname is not written yet.");
             }
+
+            [Fact]
+            public void Enum_suggestions_can_be_configured_with_list_clear()
+            {
+                var argument = new Argument<DayOfWeek?>();
+                argument.Suggestions.Clear();
+                argument.Suggestions.Add(new[] { "mon", "tues", "wed", "thur", "fri", "sat", "sun" });
+                var command = new Command("the-command")
+                {
+                    argument
+                };
+
+                var suggestions = command.Parse("the-command s")
+                                         .GetSuggestions();
+
+                suggestions.Should().BeEquivalentTo("sat", "sun","tues");
+            }
+
+            [Fact]
+            public void Enum_suggestions_can_be_configured_without_list_clear()
+            {
+                var command = new Command("the-command")
+                {
+                    new Argument<DayOfWeek?>()
+                    {
+                        Suggestions = { "mon", "tues", "wed", "thur", "fri", "sat", "sun" }
+                    }
+                };
+
+                var suggestions = command.Parse("the-command s")
+                                         .GetSuggestions();
+
+                suggestions
+                    .Should()
+                    .BeEquivalentTo(
+                        "sat",
+                        nameof(DayOfWeek.Saturday),
+                        "sun", nameof(DayOfWeek.Sunday),
+                        "tues",
+                        nameof(DayOfWeek.Tuesday),
+                        nameof(DayOfWeek.Thursday),
+                        nameof(DayOfWeek.Wednesday));
+            }
         }
     }
 }

src/System.CommandLine/Argument.cs

@@ -12,8 +12,6 @@ namespace System.CommandLine
     public class Argument : Symbol, IArgument
     {
         private Func<ArgumentResult, object?>? _defaultValueFactory;
-        private readonly List<string> _suggestions = new List<string>();
-        private readonly List<ISuggestionSource> _suggestionSources = new List<ISuggestionSource>();
         private IArgumentArity? _arity;
         private TryConvertArgument? _convertArguments;
         private Type _argumentType = typeof(void);
@@ -109,6 +107,24 @@ bool DefaultConvert(SymbolResult symbol, out object value)
             set => _convertArguments = value;
         }
 
+
+        private List<ISuggestionSource>? _suggestions = null;
+        public List<ISuggestionSource> Suggestions
+        { 
+            get
+            {
+                if (_suggestions is null)
+                {
+                    _suggestions = new List<ISuggestionSource>()
+                    {
+                        SuggestionSource.ForType(ArgumentType)
+                    };
+                }
+
+                return _suggestions;
+            }
+        }
+
         public Type ArgumentType
         {
             get => _argumentType;
@@ -158,36 +174,6 @@ public void SetDefaultValueFactory(Func<ArgumentResult, object?> getDefaultValue
 
         internal static Argument None => new Argument { Arity = ArgumentArity.Zero };
 
-        public void AddSuggestions(IReadOnlyCollection<string> suggestions)
-        {
-            if (suggestions is null)
-            {
-                throw new ArgumentNullException(nameof(suggestions));
-            }
-
-            _suggestions.AddRange(suggestions);
-        }
-
-        public void AddSuggestionSource(ISuggestionSource suggest)
-        {
-            if (suggest is null)
-            {
-                throw new ArgumentNullException(nameof(suggest));
-            }
-
-            _suggestionSources.Add(suggest);
-        }
-
-        public void AddSuggestionSource(Suggest suggest)
-        {
-            if (suggest is null)
-            {
-                throw new ArgumentNullException(nameof(suggest));
-            }
-
-            AddSuggestionSource(new AnonymousSuggestionSource(suggest));
-        }
-
         internal void AddAllowedValues(IEnumerable<string> values)
         {
             if (AllowedValues is null)
@@ -200,17 +186,10 @@ internal void AddAllowedValues(IEnumerable<string> values)
 
         public override IEnumerable<string?> GetSuggestions(string? textToMatch = null)
         {
-            var fixedSuggestions = _suggestions;
-
-            var dynamicSuggestions = _suggestionSources
+            var dynamicSuggestions = Suggestions
                 .SelectMany(source => source.GetSuggestions(textToMatch));
 
-            var typeSuggestions = SuggestionSource.ForType(ArgumentType)
-                                                  .GetSuggestions(textToMatch);
-
-            return fixedSuggestions
-                   .Concat(dynamicSuggestions)
-                   .Concat(typeSuggestions)
+            return dynamicSuggestions
                    .Distinct()
                    .OrderBy(c => c, StringComparer.OrdinalIgnoreCase)
                    .Containing(textToMatch);

src/System.CommandLine/ArgumentExtensions.cs

@@ -3,9 +3,9 @@
 
 using System.Collections.Generic;
 using System.CommandLine.Parsing;
-using System.CommandLine.Suggestions;
 using System.Linq;
 using System.IO;
+using System.CommandLine.Suggestions;
 
 namespace System.CommandLine
 {
@@ -17,30 +17,11 @@ public static TArgument FromAmong<TArgument>(
             where TArgument : Argument
         {
             argument.AddAllowedValues(values);
-            argument.AddSuggestions(values);
+            argument.Suggestions.Add(values);
 
             return argument;
         }
 
-        public static TArgument WithSuggestions<TArgument>(
-            this TArgument argument,
-            params string[] suggestions)
-            where TArgument : Argument
-        {
-            argument.AddSuggestions(suggestions);
-
-            return argument;
-        }
-
-        public static TArgument WithSuggestionSource<TArgument>(
-            this TArgument argument,
-            Suggest suggest)
-            where TArgument : Argument
-        {
-            argument.AddSuggestionSource(suggest);
-
-            return argument;
-        }
         public static Argument<FileInfo> ExistingOnly(this Argument<FileInfo> argument)
         {
             argument.AddValidator(symbol =>

src/System.CommandLine/OptionExtensions.cs

@@ -1,4 +1,4 @@
-// Copyright (c) .NET Foundation and contributors. All rights reserved.
+// Copyright (c) .NET Foundation and contributors. All rights reserved.
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
 
 using System.Collections.Generic;
@@ -17,27 +17,27 @@ public static TOption FromAmong<TOption>(
             where TOption : Option
         {
             option.Argument.AddAllowedValues(values);
-            option.Argument.AddSuggestions(values);
+            option.Argument.Suggestions.Add(values);
 
             return option;
         }
 
-        public static TOption WithSuggestions<TOption>(
+        public static TOption AddSuggestions<TOption>(
             this TOption option,
-            params string[] suggestions)
+            params string[] values)
             where TOption : Option
         {
-            option.Argument.AddSuggestions(suggestions);
+            option.Argument.Suggestions.Add(values);
 
             return option;
         }
 
-        public static TOption WithSuggestionSource<TOption>(
+        public static TOption AddSuggestion<TOption>(
             this TOption option,
             Suggest suggest)
-            where TOption : Option
+            where TOption : Option 
         {
-            option.Argument.AddSuggestionSource(suggest);
+            option.Argument.Suggestions.Add(suggest);
 
             return option;
         }