C# Generics — Animate | AI Wisdom

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🎞 ANIMATE · Mode 3 of 5 · +100 XP— C# Generics
📋Type Param
⚙️Constraints
🔄Result<T>
✅Variance
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Step 1 / 4
Speed
Type Parameters
IRepository<T> works for ANY entity — compile-time type safety without duplication💡 Analogy
Like a universal socket adapter — one interface works for different plug types.
Instead of IOrderRepository and IProductRepository separately, one IRepository<T> handles any type T. Eliminates duplicate code while keeping type safety.
Console Output
> IRepository<Order>: works for orders
> IRepository<Product>: works for products
> Same interface, compile-time type-safe, zero duplication
●Generics.cs
Type ParametersL1–8
1// Generic repository with constraints
2public interface IRepository<T> where T : Entity
3{
4    Task<T?> GetByIdAsync(Guid id);
5    Task<IEnumerable<T>> GetAllAsync();
6    Task AddAsync(T entity);
7    Task UpdateAsync(T entity);
8}
9 
10// Generic result type — avoids exceptions for expected failures
11public class Result<T>
12{
13    public T? Value { get; private init; }
14    public string? Error { get; private init; }
15    public bool IsSuccess => Error is null;
16 
17    public static Result<T> Ok(T value) => new() { Value = value };
18    public static Result<T> Fail(string error) => new() { Error = error };
19}
20 
21// Generic method with multiple constraints
22public static T FindOrThrow<T>(IEnumerable<T> items, Func<T, bool> predicate)
23    where T : class
24{
25    return items.FirstOrDefault(predicate)
26        ?? throw new NotFoundException($"{typeof(T).Name} not found");
27}
28 
29// Covariance (out): IEnumerable<Dog> assignable to IEnumerable<Animal>
30// Contravariance (in): IComparer<Animal> usable as IComparer<Dog>
31IEnumerable<string> strings = new List<string> { "a", "b" };
32IEnumerable<object> objects = strings;   // covariant ✅
33 
34// Generic extension method
35public static class Extensions
36{
37    public static IEnumerable<T> WhereNotNull<T>(this IEnumerable<T?> source)
38        where T : class
39        => source.Where(x => x is not null)!;
40}
40 lines
Timeline — 4 Steps
Type Parameters
IRepository<T> works for ANY entity — compile-time type safety without duplication💡 Analogy
Like a universal socket adapter — one interface works for different plug types.
Instead of IOrderRepository and IProductRepository separately, one IRepository<T> handles any type T. Eliminates duplicate code while keeping type safety.
Console Output
> IRepository<Order>: works for orders
> IRepository<Product>: works for products
> Same interface, compile-time type-safe, zero duplication

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Discussion

IRepository<T> works for ANY entity — compile-time type safety without duplication

💡 Analogy

Like a universal socket adapter — one interface works for different plug types.

Instead of IOrderRepository and IProductRepository separately, one IRepository<T> handles any type T. Eliminates duplicate code while keeping type safety.

Console Output

> IRepository<Order>: works for orders
> IRepository<Product>: works for products
> Same interface, compile-time type-safe, zero duplication

IRepository<T> works for ANY entity — compile-time type safety without duplication

💡 Analogy

Like a universal socket adapter — one interface works for different plug types.

Instead of IOrderRepository and IProductRepository separately, one IRepository<T> handles any type T. Eliminates duplicate code while keeping type safety.

Console Output

> IRepository<Order>: works for orders
> IRepository<Product>: works for products
> Same interface, compile-time type-safe, zero duplication