damien-o / enumconstraints.fody

Validates enum property value.

EnumConstraints.Fody

Validates enum property value.

See Milestones for release notes.

This is an add-in for Fody

It is expected that all developers using Fody become a Patron on OpenCollective. See Licensing/Patron FAQ for more information.

Usage

See also Fody usage.

NuGet installation

Install the EnumConstraints.Fody NuGet package and update the Fody NuGet package:

PM> Install-Package Fody
PM> Install-Package EnumConstraints.Fody

The Install-Package Fody is required since NuGet always defaults to the oldest, and most buggy, version of any dependency.

Add to FodyWeavers.xml

Add <EnumConstraints/> to FodyWeavers.xml

<Weavers>
  <EnumConstraints/>
</Weavers>

What it does

• Looks for all classes with Properties.
• Generates a new implementations of Set and Get methods.
• Replaces orginal implementations with the new ones.
• The new implementations are using the originals implementations under the hood

Behavior

public enum Status
{
    Value1,
    Value2,
}

public class Sample
{
    public Status Status { get; set;}
}

var sample = new();

sample.Status = Status.Value1; // Valid

sample.Status = (Status)10; // Throws an InvalidEnumValueException

How it works

The orginal lowered code

public class Sample
{
    private Status <Status>k__BackingField;

    public Status Status
    {
        get; // Calls get_Status
        set; // Calls set_Status
    }

    public Status get_Status()
    {
        return <Status>k__BackingField;
    }
    public void set_Status(Status value)
    {
        <Status>k__BackingField = value;
    }
}

What gets compiled

public class Sample
{
    private StringComparison <Status>k__BackingField;

    public Status Status
    {
        get; // Calls get_Status
        set; // Calls set_Status
    }

    public Status get_Status()
    {
        var value = get_Status_Unchecked();
        InvalidEnumValueException.ThrowIfInvalid(value);
        return value;
    }

    public void set_Status(Status value)
    {
        InvalidEnumValueException.ThrowIfInvalid(value);
        set_Status_Unchecked(value);
    }

    public Status get_Status_Unchecked
    {
        return <Status>k__BackingField;
    }
    public void set_Status_Unchecked(Status value)
    {
        <Status>k__BackingField = value;
    }
}

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