ZeroAlloc.ValueObjects 1.1.1

ZeroAlloc.ValueObjects

Zero-allocation source-generated ValueObject equality for your existing domain types.

Same performance as record — without forcing the record keyword on your domain model.

The problem

CSharpFunctionalExtensions.ValueObject uses IEnumerable<object> GetEqualityComponents() for equality. Every Equals() or GetHashCode() call allocates an iterator state machine and boxes every value-type property. In hot paths — dictionary keys, HashSets, LINQ grouping — this creates significant GC pressure.

Why not just use record?

record gives you zero-allocation equality, but comes with trade-offs:

If your domain model uses regular classes, adding [ValueObject] to an existing partial class is all you need — no refactoring, no change in type hierarchy.

Install

dotnet add package ZeroAlloc.ValueObjects

Usage

// Works on your existing partial class — no keyword changes
[ValueObject]
public partial class Money
{
    public decimal Amount { get; }
    public string Currency { get; }
}

// Or as a struct
[ValueObject]
public partial struct CustomerId
{
    public Guid Value { get; }
}

// Generated: Equals, GetHashCode (HashCode.Combine), ==, !=, ToString — zero alloc

Benchmarks

ZeroAlloc.ValueObjects matches record and record struct performance exactly. The only allocating variant is CSharpFunctionalExtensions.ValueObject.

Run your own benchmarks:

dotnet run -c Release --project benchmarks/ZeroAlloc.ValueObjects.Benchmarks

Attributes

Default member selection

All public properties with a getter participate by default. If any property is marked [EqualityMember], the mode switches to opt-in and only marked properties are included.

[ValueObject]
public partial class Address
{
    [EqualityMember] public string Street { get; }
    [EqualityMember] public string City { get; }
    public string Notes { get; }  // excluded — not marked
}

[ValueObject]
public partial class Product
{
    public string Name { get; }
    [IgnoreEqualityMember] public string InternalCode { get; }  // excluded
}

Generated output

For each [ValueObject] type the generator emits:

• bool Equals(object? obj) — direct type check, no boxing
• bool Equals(T other) — IEquatable<T> fast path
• int GetHashCode() — HashCode.Combine(...) for ≤8 props, incremental HashCode.Add() for 9+
• operator == / operator !=
• string ToString() — "Money { Amount = 10, Currency = USD }"

License

MIT