ReflectionIT.PropertyThrowGenerator 0.2.0-beta

ReflectionIT.PropertyThrowGenerator

ReflectionIT.PropertyThrowGenerator is a source generator that adds validation to partial properties annotated with [ThrowIf...] attributes.

The generated setters call the appropriate Argument...Exception.ThrowIf... helper methods before assigning the value.

NuGet package

Package	Version
ReflectionIT.PropertyThrowGenerator

Requirements

• LangVersion must be C# 14.0 or higher because the generated code uses the field keyword.
• TargetFramework must be .NET 8.0 or higher because the generated code uses ArgumentOutOfRangeException throw helper methods.

How it works

1. Add the NuGet package to your project.
2. Annotate a partial property with one or more [ThrowIf...] attributes.
3. The generator emits the implementation part of the property and inserts the required validation logic into the set or init accessor.

If a ThrowIf... attribute is used on a non-partial property, the analyzer reports a diagnostic.

Example

After installing the package, write code like this:

using ReflectionIT.PropertyThrowGenerator.Attributes;

partial class Employee {

    [ThrowIfNull]
    public required partial string Name { get; set; }

    [ThrowIfNull]
    [ThrowIfGreaterThan("London")]
    public partial string City { get; set; } = string.Empty;

    [ThrowIfGreaterThanOrEqual(16)]
    public partial int Age { get; set; }

    // Decimal attribute arguments are not supported directly, so use a string literal instead.
    [ThrowIfGreaterThan("1234.56M")]
    [ThrowIfNegative]
    public partial decimal Salary { get; set; }

}

This generates a partial class with four validated properties:

partial class Employee
{
    public required partial string Name {
        get;
        set {
            global::System.ArgumentNullException.ThrowIfNull(value);
            field = value;
        }
    }

    public partial string City {
        get;
        set {
            global::System.ArgumentNullException.ThrowIfNull(value);
            global::System.ArgumentOutOfRangeException.ThrowIfGreaterThan(value, "London");
            field = value;
        }
    }

    public partial int Age {
        get;
        set {
            global::System.ArgumentOutOfRangeException.ThrowIfGreaterThanOrEqual(value, 16);
            field = value;
        }
    }

    public partial decimal Salary {
        get;
        set {
            global::System.ArgumentOutOfRangeException.ThrowIfGreaterThan(value, 1234.56M);
            global::System.ArgumentOutOfRangeException.ThrowIfNegative(value);
            field = value;
        }
    }
}

Attributes

• ThrowIfEqualAttribute
• ThrowIfGreaterThanAttribute
• ThrowIfGreaterThanOrEqualAttribute
• ThrowIfLessThanAttribute
• ThrowIfLessThanOrEqualAttribute
• ThrowIfNegativeAttribute
• ThrowIfNegativeOrZeroAttribute
• ThrowIfNotEqualAttribute
• ThrowIfNullAttribute
• ThrowIfNullOrEmptyAttribute
• ThrowIfNullOrWhiteSpaceAttribute
• ThrowIfZeroAttribute

Analyzer rules

The package also includes analyzers that help detect unsupported usage at compile time.

PTG001: C# language version is not supported

This rule is reported when the consuming project does not use C# 14.0 or later.

The generator requires C# 14 because the generated code uses the field keyword.

PTG002: ThrowIf attributes require partial properties

This rule is reported when one of the ThrowIf... attributes is used on a property that is not declared partial.

Only partial properties are supported because the generator emits the implementation part of the property.

License

This project is licensed under the MIT License - see the LICENSE file for details.