This library provides some interfaces, classes, Roslyn Source Generators, Roslyn Analyzers and Roslyn CodeFixes for implementation of Smart Enums, Value Objects and Discriminated Unions.
See wiki for more documentation.
Smart Enums:
Value objects:
- Version 8:
- C# 11 (or higher) for generated code
- SDK 8.0.400 (or higher) for building projects
- Version 7:
- C# 11 (or higher) for generated code
- SDK 7.0.401 (or higher) for building projects
Install: Install-Package Thinktecture.Runtime.Extensions
Documentation: Smart Enums
Features:
- Roslyn Analyzers and CodeFixes help the developers to implement the Smart Enums correctly
- Allows iteration over all items
- Allows custom properties and methods
- Switch-case/Map
- Provides appropriate constructor, based on the specified properties/fields
- Provides means for lookup, cast and type conversion from key-type to Smart Enum and vice versa
- Provides proper implementation of
Equals
,GetHashCode
,ToString
and equality comparison via==
and!=
- Provides implementation of
IComparable
,IComparable<T>
,IFormattable
,IParsable<T>
and comparison operators<
,<=
,>
,>=
(if applicable to the underlying type) - Choice between always-valid and maybe-valid Smart Enum
- Smart Enum can also be keyless, i.e. without a key member
- Makes use of abstract static members
- Derived types can be generic
- Allows custom validation of constructor arguments
- Allows changing the key member name, kind and access modifier, which holds the underlying value - thanks to Roslyn Source Generator
- Allows custom key equality comparer and custom comparer
- JSON support (
System.Text.Json
andNewtonsoft.Json
) - Support for Minimal Api Parameter Binding and ASP.NET Core Model Binding
- Entity Framework Core support (
ValueConverter
) - MessagePack support (
IMessagePackFormatter
) - Logging for debugging or getting insights
Definition of a 2 Smart Enums without any custom properties and methods. All other features mentioned above are generated by the Roslyn Source Generators in the background.
// Smart Enum with a string as the underlying type
[SmartEnum<string>]
public sealed partial class ProductType
{
public static readonly ProductType Groceries = new("Groceries");
public static readonly ProductType Housewares = new("Housewares");
}
// Smart Enum with an int as the underlying type
[SmartEnum<int>]
public sealed partial class ProductGroup
{
public static readonly ProductGroup Apple = new(1);
public static readonly ProductGroup Orange = new(2);
}
// Smart Enum without identifier (keyless)
[SmartEnum]
public sealed partial class SalesCsvImporterType
{
public static readonly SalesCsvImporterType Daily = new(articleIdIndex: 0, volumeIndex: 2);
public static readonly SalesCsvImporterType Monthly = new(articleIdIndex: 2, volumeIndex: 0);
public int ArticleIdIndex { get; }
public int VolumeIndex { get; }
}
Behind the scenes a Roslyn Source Generator generates additional code. Some of the features that are now available are ...
// A private constructor which takes the key "Groceries" and additional members (if we had any)
[SmartEnum<string>]
public sealed partial class ProductType
{
public static readonly ProductType Groceries = new("Groceries");
...
------------
// A property for iteration over all items
IReadOnlyList<ProductType> allTypes = ProductType.Items;
------------
// Getting the item with specific name, i.e. its key.
// Throws UnknownEnumIdentifierException if the provided key doesn't belong to any item
ProductType productType = ProductType.Get("Groceries");
// Alternatively, using an explicit cast (behaves the same as "Get")
ProductType productType = (ProductType)"Groceries";
------------
// the same as above but returns a bool instead of throwing an exception (dictionary-style)
bool found = ProductType.TryGet("Groceries", out ProductType? productType);
------------
// similar to TryGet but accepts `IFormatProvider` and returns a ValidationError instead of a boolean.
ValidationError? validationError = ProductType.Validate("Groceries", null, out ProductType? productType);
if (validationError is null)
{
logger.Information("Product type {Type} found with Validate", productType);
}
else
{
logger.Warning("Failed to fetch the product type with Validate. Validation error: {validationError}", validationError.ToString());
}
------------
// implicit conversion to the type of the key
string key = ProductType.Groceries; // "Groceries"
------------
// Equality comparison
bool equal = ProductType.Groceries.Equals(ProductType.Groceries);
------------
// Equality comparison with '==' and '!='
bool equal = ProductType.Groceries == ProductType.Groceries;
bool notEqual = ProductType.Groceries != ProductType.Groceries;
------------
// Hash code
int hashCode = ProductType.Groceries.GetHashCode();
------------
// 'ToString' implementation
string key = ProductType.Groceries.ToString(); // "Groceries"
------------
ILogger logger = ...;
// Switch-case (with "Action")
productType.Switch(groceries: () => logger.Information("Switch with Action: Groceries"),
housewares: () => logger.Information("Switch with Action: Housewares"));
// Switch-case with parameter (Action<TParam>) to prevent closures
productType.Switch(logger,
groceries: static l => l.Information("Switch with Action: Groceries"),
housewares: static l => l.Information("Switch with Action: Housewares"));
// Switch case returning a value (Func<TResult>)
var returnValue = productType.Switch(groceries: static () => "Switch with Func<T>: Groceries",
housewares: static () => "Switch with Func<T>: Housewares");
// Switch case with parameter returning a value (Func<TParam, TResult>) to prevent closures
var returnValue = productType.Switch(logger,
groceries: static l => "Switch with Func<T>: Groceries",
housewares: static l => "Switch with Func<T>: Housewares");
// Map an item to another instance
returnValue = productType.Map(groceries: "Map: Groceries",
housewares: "Map: Housewares");
------------
// Implements IParsable<T> which is especially helpful with minimal apis.
bool parsed = ProductType.TryParse("Groceries", null, out ProductType? parsedProductType);
------------
// Implements IFormattable if the underlyng type (like int) is an IFormattable itself.
var formatted = ProductGroup.Fruits.ToString("000", CultureInfo.InvariantCulture); // 001
------------
// Implements IComparable and IComparable<T> if the key member type (like int) is an IComparable itself.
var comparison = ProductGroup.Fruits.CompareTo(ProductGroup.Vegetables); // -1
// Implements comparison operators (<,<=,>,>=) if the underlyng type (like int) has comparison operators itself.
var isBigger = ProductGroup.Fruits > ProductGroup.Vegetables;
Definition of a new Smart Enum with 1 custom property RequiresFoodVendorLicense
and 1 method Do
with different behaviors for different enum items.
[SmartEnum<string>]
public partial class ProductType
{
public static readonly ProductType Groceries = new("Groceries", requiresFoodVendorLicense: true);
public static readonly ProductType Housewares = new HousewaresProductType();
public bool RequiresFoodVendorLicense { get; }
public virtual void Do()
{
// do default stuff
}
private sealed class HousewaresProductType : ProductType
{
public HousewaresProductType()
: base("Housewares", requiresFoodVendorLicense: false)
{
}
public override void Do()
{
// do special stuff
}
}
}
Install: Install-Package Thinktecture.Runtime.Extensions
Documentation: Value Objects
Features:
- Roslyn Analyzers and CodeFixes help the developers to implement the Value Objects correctly
- Choice between Simple Value Objects and Complex Value Objects
- Allows custom fields, properties and methods
- Provides appropriate factory methods for creation of new value objects based on the specified properties/fields
- Factory methods can be renamed
- Allows custom validation of constructor and factory method arguments
- Allows custom type to pass validation error(s)
- [Simple Value Objects only] Allows cast and type conversion from key-member type to Value Object and vice versa
- [Simple Value Objects only] Provides an implementation of
IFormattable
if the key member is anIFormattable
- Provides proper implementation of
Equals
,GetHashCode
,ToString
and equality comparison via==
and!=
- Provides implementation of
IComparable
,IComparable<T>
,IFormattable
,IParsable<T>
and comparison operators<
,<=
,>
,>=
- Allows custom equality comparison and custom comparer
- Configurable handling of null and empty strings
- JSON support (
System.Text.Json
andNewtonsoft.Json
) - Support for Minimal Api Parameter Binding and ASP.NET Core Model Binding
- Entity Framework Core support (
ValueConverter
) - MessagePack support (
IMessagePackFormatter
) - Logging for debugging or getting insights
A simple value object has 1 field/property only, i.e., it is kind of wrapper for another (primitive) type. The main use case is to prevent creation of values/instances which are considered invalid according to some rules. In DDD (domain-driven design), working with primitive types, like string, directly is called primitive obsession and should be avoided.
Most simple value objects with a key member of type string
and another one (which is a struct) with an int
.
[ValueObject<string>]
public sealed partial class ProductName
{
}
[ValueObject<int>]
public readonly partial struct Amount
{
}
After the implementation of a value object, a Roslyn source generator kicks in and implements the rest. Following API is available from now on.
// Factory method for creation of new instances.
// Throws ValidationException if the validation fails (if we had any)
ProductName apple = ProductName.Create("Apple");
// Alternatively, using an explicit cast, which behaves the same way as calling "ProductName.Create"
ProductName apple = (ProductName)"Apple";
-----------
// The same as above but returns a bool instead of throwing an exception (dictionary-style)
bool created = ProductName.TryCreate("Chocolate", out ProductName? chocolate);
-----------
// Similar to TryCreate but returns a ValidationError instead of a boolean.
ValidationError? validationError = ProductName.Validate("Chocolate", null, out var chocolate);
if (validationError is null)
{
logger.Information("Product name {Name} created", chocolate);
}
else
{
logger.Warning("Failed to create product name. Validation result: {validationError}", validationError.ToString());
}
-----------
// Implicit conversion to the type of the key member
string valueOfTheProductName = apple; // "Apple"
-----------
// Equality comparison compares the key member using default comparer by default.
// Key members of type `string` are compared with 'StringComparer.OrdinalIgnoreCase' by default.
bool equal = apple.Equals(apple);
-----------
// Equality comparison operators: '==' and '!='
bool equal = apple == apple;
bool notEqual = apple != apple;
-----------
// Hash code: combined hash code of type and key member.
// Strings are using 'StringComparer.OrdinalIgnoreCase' by default.
int hashCode = apple.GetHashCode();
-----------
// 'ToString' implementation return the string representation of the key member
string value = apple.ToString(); // "Apple"
------------
// Implements IParsable<T> which is especially helpful with minimal apis.
bool success = ProductName.TryParse("New product name", null, out var productName);
ProductName productName = ProductName.Parse("New product name", null);
------------
// Implements "IFormattable" if the key member is an "IFormattable".
Amount amount = Amount.Create(42);
string formattedValue = amount.ToString("000", CultureInfo.InvariantCulture); // "042"
------------
// Implements "IComparable<ProductName>" if the key member is an "IComparable",
// or if custom comparer is provided.
Amount amount = Amount.Create(1);
Amount otherAmount = Amount.Create(2);
int comparison = amount.CompareTo(otherAmount); // -1
------------
// Implements comparison operators (<,<=,>,>=) if the key member has comparison operators itself.
bool isBigger = amount > otherAmount;
// Implements comparison operators to compare the value object with an instance of key-member-type,
// if "ComparisonOperators" is set "OperatorsGeneration.DefaultWithKeyTypeOverloads"
bool isBigger = amount > 2;
------------
// Implements addition / subtraction / multiplication / division if the key member supports corresponding operators
Amount sum = amount + otherAmount;
// Implements operators that accept an instance of key-member-type,
// if the "OperatorsGeneration" is set "DefaultWithKeyTypeOverloads"
Amount sum = amount + 2;
------------
// Provides a static default value "Empty" (similar to "Guid.Empty"), if the value object is a struct
Amount defaultValue = Amount.Empty; // same as "Amount defaultValue = default;"
A complex value object is an immutable class
or a readonly struct
with a ComplexValueObjectAttribute
. Complex value object usually has multiple readonly fields/properties.
A simple example would be a Boundary
with 2 properties. One property is the lower boundary and the other is the upper boundary. Yet again, we skip the validation at the moment.
[ComplexValueObject]
public sealed partial class Boundary
{
public decimal Lower { get; }
public decimal Upper { get; }
}
The rest is implemented by a Roslyn source generator, providing the following API:
// Factory method for creation of new instances.
// Throws ValidationException if the validation fails (if we had any)
Boundary boundary = Boundary.Create(lower: 1, upper: 2);
-----------
// the same as above but returns a bool instead of throwing an exception (dictionary-style)
bool created = Boundary.TryCreate(lower: 1, upper: 2, out Boundary? boundary);
-----------
// similar to TryCreate but returns a ValidationError instead of a boolean.
ValidationError? validationError = Boundary.Validate(lower: 1, upper: 2, out Boundary? boundary);
if (validationError is null)
{
logger.Information("Boundary {Boundary} created", boundary);
}
else
{
logger.Warning("Failed to create boundary. Validation result: {validationError}", validationError.ToString());
}
-----------
// Equality comparison compares the members using default or custom comparers.
// Strings are compared with 'StringComparer.OrdinalIgnoreCase' by default.
bool equal = boundary.Equals(boundary);
-----------
// Equality comparison with '==' and '!='
bool equal = boundary == boundary;
bool notEqual = boundary != boundary;
-----------
// Hash code of the members according default or custom comparers
int hashCode = boundary.GetHashCode();
-----------
// 'ToString' implementation
string value = boundary.ToString(); // "{ Lower = 1, Upper = 2 }"
Install: Install-Package Thinktecture.Runtime.Extensions
Documentation: Discriminated Unions
Features:
- Roslyn Analyzers and CodeFixes help the developers to implement the Discriminated Unions correctly
- Provides proper implementation of
Equals
,GetHashCode
,ToString
and equality comparison via==
and!=
- Switch-Case/Map
- Renaming of properties
- Definition of nullable reference types
Definition of a basic union with 2 types using a class
, a struct
or ref struct
:
// class
[Union<string, int>]
public partial class TextOrNumber;
// struct
[Union<string, int>]
public partial struct TextOrNumber;
// ref struct
[Union<string, int>]
public ref partial struct TextOrNumber;
// Up to 5 types
[Union<string, int, bool, Guid, char>]
public partial class MyUnion;
Behind the scenes a Roslyn Source Generator generates additional code. Some of the features that are now available are ...
// Implicit conversion from one of the defined generics.
TextOrNumber textOrNumberFromString = "text";
TextOrNumber textOrNumberFromInt = 42;
// Check the type of the value.
// By default, the properties are named using the name of the type (`String`, `Int32`)
bool isText = textOrNumberFromString.IsString;
bool isNumber = textOrNumberFromString.IsInt32;
// Getting the typed value.
// Throws "InvalidOperationException" if the current value doesn't match the calling property.
// By default, the properties are named using the name of the type (`String`, `Int32`)
string text = textOrNumberFromString.AsString;
int number = textOrNumberFromInt.AsInt32;
// Alternative approach is to use explicit cast.
// Behavior is identical to methods "As..."
string text = (string)textOrNumberFromString;
int number = (int)textOrNumberFromInt;
// Getting the value as object, i.e. untyped.
object value = textOrNumberFromString.Value;
// Implementation of Equals, GetHashCode and ToString
// PLEASE NOTE: Strings are compared using "StringComparison.OrdinalIgnoreCase" by default! (configurable)
bool equals = textOrNumberFromInt.Equals(textOrNumberFromString);
int hashCode = textOrNumberFromInt.GetHashCode();
string toString = textOrNumberFromInt.ToString();
// Equality comparison operators
bool equal = textOrNumberFromInt == textOrNumberFromString;
bool notEqual = textOrNumberFromInt != textOrNumberFromString;
There are multiple overloads of switch-cases: with Action
, Func<T>
and concrete values.
To prevent closures, you can pass a value to method Switch
, which is going to be passed to provided callback (Action
/Func<T>
).
By default, the names of the method arguments are named after the type specified by UnionAttribute<T1, T2>
.
Reserved C# keywords (like string
) must string with @
(like @string
, @default
, etc.).
// With "Action"
textOrNumberFromString.Switch(@string: s => logger.Information("[Switch] String Action: {Text}", s),
int32: i => logger.Information("[Switch] Int Action: {Number}", i));
// With "Action". Logger is passed as additional parameter to prevent closures.
textOrNumberFromString.Switch(logger,
@string: static (l, s) => l.Information("[Switch] String Action with logger: {Text}", s),
int32: static (l, i) => l.Information("[Switch] Int Action with logger: {Number}", i));
// With "Func<T>"
var switchResponse = textOrNumberFromInt.Switch(@string: static s => $"[Switch] String Func: {s}",
int32: static i => $"[Switch] Int Func: {i}");
// With "Func<T>" and additional argument to prevent closures.
var switchResponseWithContext = textOrNumberFromInt.Switch(123.45,
@string: static (value, s) => $"[Switch] String Func with value: {ctx} | {s}",
int32: static (value, i) => $"[Switch] Int Func with value: {ctx} | {i}");
// Use `Map` instead of `Switch` to return concrete values directly.
var mapResponse = textOrNumberFromString.Map(@string: "[Map] Mapped string",
int32: "[Map] Mapped int");
Use T1Name
/T2Name
of the UnionAttribute
to get more meaningful names.
[Union<string, int>(T1Name = "Text",
T2Name = "Number")]
public partial class TextOrNumber;
The properties and method arguments are renamed accordingly:
bool isText = textOrNumberFromString.IsText;
bool isNumber = textOrNumberFromString.IsNumber;
string text = textOrNumberFromString.AsText;
int number = textOrNumberFromInt.AsNumber;
textOrNumberFromString.Switch(text: s => logger.Information("[Switch] String Action: {Text}", s),
number: i => logger.Information("[Switch] Int Action: {Number}", i));