csharpessentials-clone

name	csharpessentials-clone
description	Use when entities need deep-copy semantics — implement ICloneable<T> on domain objects, then call .Clone() on IEnumerable<T> or IQueryable<T> collections to produce independent deep copies of every element.

CSharpEssentials.Clone

Typed deep-copy contract for domain objects. ICloneable<T> is covariant and type-safe — unlike System.ICloneable which returns object.

Installation

dotnet add package CSharpEssentials.Clone

Namespace

using CSharpEssentials.Clone;

---

Implement ICloneable<T>

public class Product : ICloneable<Product>
{
    public int Id       { get; init; }
    public string Name  { get; init; } = "";
    public List<Tag> Tags { get; init; } = new();

    public Product Clone() => new()
    {
        Id   = Id,
        Name = Name,
        Tags = Tags.Select(t => t.Clone()).ToList()  // deep-copy child collections too
    };
}

public class Tag : ICloneable<Tag>
{
    public string Value { get; init; } = "";
    public Tag Clone() => new() { Value = Value };
}

---

Clone Collections

Extension methods call Clone() on every element:

// IEnumerable<T> where T : ICloneable<T>
IEnumerable<Product> copies = products.Clone();

// IQueryable<T> where T : ICloneable<T>
IQueryable<Product> projected = dbSet.Clone();

---

Typical Use Case

Snapshot EF Core results before applying in-memory transformations, without mutating tracked entities:

var snapshot = await _db.Products
    .Where(p => p.CategoryId == id)
    .ToListAsync();

var working = snapshot.Clone();  // independent deep copies — mutations don't affect EF tracking
ApplyDiscounts(working);

---

Best Practices

• Always deep-copy nested collections inside Clone() — a shallow copy defeats the purpose
• ICloneable<T> is covariant (out T) — a Product : ICloneable<Product> satisfies ICloneable<object> if needed
• Consider using record types with with expressions for immutable value objects instead of ICloneable<T>
• ICloneable<T> is most valuable for mutable domain objects that are tracked by EF Core