From 5518bf56ad6905c300bc0941739415644c8a77c4 Mon Sep 17 00:00:00 2001 From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com> Date: Wed, 30 Jul 2025 18:43:55 +0000 Subject: [PATCH 1/6] Initial plan From c366f667c5b82616d94ece0efc977fdfd212972d Mon Sep 17 00:00:00 2001 From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com> Date: Wed, 30 Jul 2025 18:55:11 +0000 Subject: [PATCH 2/6] Add clarification and example for abstract classes with implemented methods Co-authored-by: BillWagner <493969+BillWagner@users.noreply.github.com> --- .../language-reference/keywords/abstract.md | 22 ++++- .../keywords/snippets/abstract/Program.cs | 95 +++++++++++++++++++ .../snippets/abstract/abstract.csproj | 10 ++ 3 files changed, 124 insertions(+), 3 deletions(-) create mode 100644 docs/csharp/language-reference/keywords/snippets/abstract/Program.cs create mode 100644 docs/csharp/language-reference/keywords/snippets/abstract/abstract.csproj diff --git a/docs/csharp/language-reference/keywords/abstract.md b/docs/csharp/language-reference/keywords/abstract.md index 22adc9ad21660..52137e15e3512 100644 --- a/docs/csharp/language-reference/keywords/abstract.md +++ b/docs/csharp/language-reference/keywords/abstract.md @@ -12,8 +12,22 @@ ms.assetid: b0797770-c1f3-4b4d-9441-b9122602a6bb # abstract (C# Reference) The `abstract` modifier indicates that the thing being modified has a missing or incomplete implementation. The abstract modifier can be used with classes, methods, properties, indexers, and events. Use the `abstract` modifier in a class declaration to indicate that a class is intended only to be a base class of other classes, not instantiated on its own. Members marked as abstract must be implemented by non-abstract classes that derive from the abstract class. + +Abstract classes can contain both abstract members (which have no implementation and must be overridden in derived classes) and fully implemented members (such as regular methods, properties, and constructors). This allows abstract classes to provide common functionality while still requiring derived classes to implement specific abstract members. -## Example 1 +## Example 1 - Abstract class with mixed members + +The following example demonstrates an abstract class that contains both implemented methods and abstract members: + +[!code-csharp[AbstractWithImplemented](snippets/abstract/Program.cs#snippet1)] + +In this example, the `Vehicle` abstract class provides: +- **Implemented members**: `GetInfo()` method, `StartEngine()` method, and constructor - these provide common functionality for all vehicles +- **Abstract members**: `Move()` method and `MaxSpeed` property - these must be implemented by each specific vehicle type + +This design allows the abstract class to provide shared functionality while ensuring that derived classes implement vehicle-specific behavior. + +## Example 2 In this example, the class `Square` must provide an implementation of `GetArea` because it derives from `Shape`: @@ -25,6 +39,8 @@ The `abstract` modifier indicates that the thing being modified has a missing or - An abstract class may contain abstract methods and accessors. +- An abstract class can also contain implemented methods, properties, fields, and other members that provide functionality to derived classes. + - It is not possible to modify an abstract class with the [sealed](./sealed.md) modifier because the two modifiers have opposite meanings. The `sealed` modifier prevents a class from being inherited and the `abstract` modifier requires a class to be inherited. - A non-abstract class derived from an abstract class must include actual implementations of all inherited abstract methods and accessors. @@ -61,7 +77,7 @@ The `abstract` modifier indicates that the thing being modified has a missing or [!code-csharp[csrefKeywordsModifiers#2](~/samples/snippets/csharp/VS_Snippets_VBCSharp/csrefKeywordsModifiers/CS/csrefKeywordsModifiers.cs#2)] -## Example 2 +## Example 3 In this example, the class `DerivedClass` is derived from an abstract class `BaseClass`. The abstract class contains an abstract method, `AbstractMethod`, and two abstract properties, `X` and `Y`. @@ -77,7 +93,7 @@ You will get an error saying that the compiler cannot create an instance of the Nonetheless, it is possible to use an abstract class constructor, as in the example below -## Example 3 +## Example 4 [!code-csharp[csrefKeywordsModifiers#27](~/samples/snippets/csharp/VS_Snippets_VBCSharp/csrefKeywordsModifiers/CS/csrefKeywordsModifiers.cs#27)] diff --git a/docs/csharp/language-reference/keywords/snippets/abstract/Program.cs b/docs/csharp/language-reference/keywords/snippets/abstract/Program.cs new file mode 100644 index 0000000000000..6174f0647dcf6 --- /dev/null +++ b/docs/csharp/language-reference/keywords/snippets/abstract/Program.cs @@ -0,0 +1,95 @@ +// +public abstract class Vehicle +{ + protected string _brand; + + // Constructor - implemented method in abstract class + public Vehicle(string brand) + { + _brand = brand; + } + + // Implemented method - provides functionality that all vehicles share + public string GetInfo() + { + return $"This is a {_brand} vehicle."; + } + + // Another implemented method + public virtual void StartEngine() + { + Console.WriteLine($"{_brand} engine is starting..."); + } + + // Abstract method - must be implemented by derived classes + public abstract void Move(); + + // Abstract property - must be implemented by derived classes + public abstract int MaxSpeed { get; } +} + +public class Car : Vehicle +{ + public Car(string brand) : base(brand) { } + + // Implementation of abstract method + public override void Move() + { + Console.WriteLine($"{_brand} car is driving on the road."); + } + + // Implementation of abstract property + public override int MaxSpeed => 200; +} + +public class Boat : Vehicle +{ + public Boat(string brand) : base(brand) { } + + // Implementation of abstract method + public override void Move() + { + Console.WriteLine($"{_brand} boat is sailing on the water."); + } + + // Implementation of abstract property + public override int MaxSpeed => 50; +} + +class Program +{ + static void Main() + { + // Cannot instantiate abstract class: Vehicle v = new Vehicle("Generic"); // Error! + + Car car = new Car("Toyota"); + Boat boat = new Boat("Yamaha"); + + // Using implemented methods from abstract class + Console.WriteLine(car.GetInfo()); + car.StartEngine(); + + // Using abstract methods implemented in derived class + car.Move(); + Console.WriteLine($"Max speed: {car.MaxSpeed} km/h"); + + Console.WriteLine(); + + Console.WriteLine(boat.GetInfo()); + boat.StartEngine(); + boat.Move(); + Console.WriteLine($"Max speed: {boat.MaxSpeed} km/h"); + } +} +/* Output: +This is a Toyota vehicle. +Toyota engine is starting... +Toyota car is driving on the road. +Max speed: 200 km/h + +This is a Yamaha vehicle. +Yamaha engine is starting... +Yamaha boat is sailing on the water. +Max speed: 50 km/h +*/ +// \ No newline at end of file diff --git a/docs/csharp/language-reference/keywords/snippets/abstract/abstract.csproj b/docs/csharp/language-reference/keywords/snippets/abstract/abstract.csproj new file mode 100644 index 0000000000000..c28018dbfdd4c --- /dev/null +++ b/docs/csharp/language-reference/keywords/snippets/abstract/abstract.csproj @@ -0,0 +1,10 @@ + + + + Exe + net8.0 + enable + enable + + + \ No newline at end of file From 69fb5a8c05d3115b45c5aa32fee2d69a4af2fffd Mon Sep 17 00:00:00 2001 From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com> Date: Thu, 31 Jul 2025 15:10:22 +0000 Subject: [PATCH 3/6] Address feedback: use expression-bodied members, update syntax, and target .NET 9 Co-authored-by: BillWagner <493969+BillWagner@users.noreply.github.com> --- .../language-reference/keywords/abstract.md | 2 +- .../keywords/snippets/abstract/Program.cs | 20 ++++--------------- .../snippets/abstract/abstract.csproj | 2 +- 3 files changed, 6 insertions(+), 18 deletions(-) diff --git a/docs/csharp/language-reference/keywords/abstract.md b/docs/csharp/language-reference/keywords/abstract.md index 52137e15e3512..b38e33521a49f 100644 --- a/docs/csharp/language-reference/keywords/abstract.md +++ b/docs/csharp/language-reference/keywords/abstract.md @@ -19,7 +19,7 @@ Abstract classes can contain both abstract members (which have no implementation The following example demonstrates an abstract class that contains both implemented methods and abstract members: -[!code-csharp[AbstractWithImplemented](snippets/abstract/Program.cs#snippet1)] +:::code language="csharp" source="snippets/abstract/Program.cs" id="snippet1"::: In this example, the `Vehicle` abstract class provides: - **Implemented members**: `GetInfo()` method, `StartEngine()` method, and constructor - these provide common functionality for all vehicles diff --git a/docs/csharp/language-reference/keywords/snippets/abstract/Program.cs b/docs/csharp/language-reference/keywords/snippets/abstract/Program.cs index 6174f0647dcf6..95914dfbb5630 100644 --- a/docs/csharp/language-reference/keywords/snippets/abstract/Program.cs +++ b/docs/csharp/language-reference/keywords/snippets/abstract/Program.cs @@ -10,16 +10,10 @@ public Vehicle(string brand) } // Implemented method - provides functionality that all vehicles share - public string GetInfo() - { - return $"This is a {_brand} vehicle."; - } + public string GetInfo() => $"This is a {_brand} vehicle."; // Another implemented method - public virtual void StartEngine() - { - Console.WriteLine($"{_brand} engine is starting..."); - } + public virtual void StartEngine() => Console.WriteLine($"{_brand} engine is starting..."); // Abstract method - must be implemented by derived classes public abstract void Move(); @@ -33,10 +27,7 @@ public class Car : Vehicle public Car(string brand) : base(brand) { } // Implementation of abstract method - public override void Move() - { - Console.WriteLine($"{_brand} car is driving on the road."); - } + public override void Move() => Console.WriteLine($"{_brand} car is driving on the road."); // Implementation of abstract property public override int MaxSpeed => 200; @@ -47,10 +38,7 @@ public class Boat : Vehicle public Boat(string brand) : base(brand) { } // Implementation of abstract method - public override void Move() - { - Console.WriteLine($"{_brand} boat is sailing on the water."); - } + public override void Move() => Console.WriteLine($"{_brand} boat is sailing on the water."); // Implementation of abstract property public override int MaxSpeed => 50; diff --git a/docs/csharp/language-reference/keywords/snippets/abstract/abstract.csproj b/docs/csharp/language-reference/keywords/snippets/abstract/abstract.csproj index c28018dbfdd4c..3477df059b152 100644 --- a/docs/csharp/language-reference/keywords/snippets/abstract/abstract.csproj +++ b/docs/csharp/language-reference/keywords/snippets/abstract/abstract.csproj @@ -2,7 +2,7 @@ Exe - net8.0 + net9.0 enable enable From 4dfee48e89a978116d8c7744e2e892d187c7c82f Mon Sep 17 00:00:00 2001 From: Bill Wagner Date: Thu, 31 Jul 2025 11:14:42 -0400 Subject: [PATCH 4/6] Update docs/csharp/language-reference/keywords/snippets/abstract/Program.cs --- .../language-reference/keywords/snippets/abstract/Program.cs | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) diff --git a/docs/csharp/language-reference/keywords/snippets/abstract/Program.cs b/docs/csharp/language-reference/keywords/snippets/abstract/Program.cs index 95914dfbb5630..acdc13b43ece0 100644 --- a/docs/csharp/language-reference/keywords/snippets/abstract/Program.cs +++ b/docs/csharp/language-reference/keywords/snippets/abstract/Program.cs @@ -4,10 +4,7 @@ public abstract class Vehicle protected string _brand; // Constructor - implemented method in abstract class - public Vehicle(string brand) - { - _brand = brand; - } + public Vehicle(string brand) => _brand = brand; // Implemented method - provides functionality that all vehicles share public string GetInfo() => $"This is a {_brand} vehicle."; From 2fd7a2a766a146461d66613ddaa3067600617d77 Mon Sep 17 00:00:00 2001 From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com> Date: Thu, 31 Jul 2025 15:33:06 +0000 Subject: [PATCH 5/6] Address feedback: move to snippets/shared, rename classes, add blank line Co-authored-by: BillWagner <493969+BillWagner@users.noreply.github.com> --- .../csharp/language-reference/keywords/abstract.md | 3 ++- .../{abstract/Program.cs => shared/Abstract.cs} | 14 ++++++++++++-- .../snippets/{abstract => shared}/abstract.csproj | 2 +- 3 files changed, 15 insertions(+), 4 deletions(-) rename docs/csharp/language-reference/keywords/snippets/{abstract/Program.cs => shared/Abstract.cs} (94%) rename docs/csharp/language-reference/keywords/snippets/{abstract => shared}/abstract.csproj (80%) diff --git a/docs/csharp/language-reference/keywords/abstract.md b/docs/csharp/language-reference/keywords/abstract.md index b38e33521a49f..a7e2418f696c2 100644 --- a/docs/csharp/language-reference/keywords/abstract.md +++ b/docs/csharp/language-reference/keywords/abstract.md @@ -19,9 +19,10 @@ Abstract classes can contain both abstract members (which have no implementation The following example demonstrates an abstract class that contains both implemented methods and abstract members: -:::code language="csharp" source="snippets/abstract/Program.cs" id="snippet1"::: +:::code language="csharp" source="snippets/shared/Abstract.cs" id="snippet1"::: In this example, the `Vehicle` abstract class provides: + - **Implemented members**: `GetInfo()` method, `StartEngine()` method, and constructor - these provide common functionality for all vehicles - **Abstract members**: `Move()` method and `MaxSpeed` property - these must be implemented by each specific vehicle type diff --git a/docs/csharp/language-reference/keywords/snippets/abstract/Program.cs b/docs/csharp/language-reference/keywords/snippets/shared/Abstract.cs similarity index 94% rename from docs/csharp/language-reference/keywords/snippets/abstract/Program.cs rename to docs/csharp/language-reference/keywords/snippets/shared/Abstract.cs index acdc13b43ece0..2daedb7fb2440 100644 --- a/docs/csharp/language-reference/keywords/snippets/abstract/Program.cs +++ b/docs/csharp/language-reference/keywords/snippets/shared/Abstract.cs @@ -1,4 +1,6 @@ // +namespace LanguageKeywords; + public abstract class Vehicle { protected string _brand; @@ -41,9 +43,9 @@ public Boat(string brand) : base(brand) { } public override int MaxSpeed => 50; } -class Program +public class AbstractExample { - static void Main() + public static void Examples() { // Cannot instantiate abstract class: Vehicle v = new Vehicle("Generic"); // Error! @@ -66,6 +68,14 @@ static void Main() Console.WriteLine($"Max speed: {boat.MaxSpeed} km/h"); } } + +class Program +{ + static void Main() + { + AbstractExample.Examples(); + } +} /* Output: This is a Toyota vehicle. Toyota engine is starting... diff --git a/docs/csharp/language-reference/keywords/snippets/abstract/abstract.csproj b/docs/csharp/language-reference/keywords/snippets/shared/abstract.csproj similarity index 80% rename from docs/csharp/language-reference/keywords/snippets/abstract/abstract.csproj rename to docs/csharp/language-reference/keywords/snippets/shared/abstract.csproj index 3477df059b152..c28018dbfdd4c 100644 --- a/docs/csharp/language-reference/keywords/snippets/abstract/abstract.csproj +++ b/docs/csharp/language-reference/keywords/snippets/shared/abstract.csproj @@ -2,7 +2,7 @@ Exe - net9.0 + net8.0 enable enable From 53182514bffb3e9b218dbd25459222e121c99f3e Mon Sep 17 00:00:00 2001 From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com> Date: Thu, 31 Jul 2025 15:41:16 +0000 Subject: [PATCH 6/6] Delete redundant abstract.csproj file as requested Co-authored-by: BillWagner <493969+BillWagner@users.noreply.github.com> --- .../keywords/snippets/shared/abstract.csproj | 10 ---------- 1 file changed, 10 deletions(-) delete mode 100644 docs/csharp/language-reference/keywords/snippets/shared/abstract.csproj diff --git a/docs/csharp/language-reference/keywords/snippets/shared/abstract.csproj b/docs/csharp/language-reference/keywords/snippets/shared/abstract.csproj deleted file mode 100644 index c28018dbfdd4c..0000000000000 --- a/docs/csharp/language-reference/keywords/snippets/shared/abstract.csproj +++ /dev/null @@ -1,10 +0,0 @@ - - - - Exe - net8.0 - enable - enable - - - \ No newline at end of file