SOLID & Design Patterns Interview Question #28

What is the Proxy Pattern?

Structural, Creational & Behavioral Patterns Junior Beginner

Quick Interview Answer

The Proxy Pattern provides a stand-in object that controls access to another object while exposing a compatible interface. The proxy can add behavior such as lazy loading, authorization, remote access, caching, or logging.

Detailed Explanation

Unlike an adapter, a proxy normally preserves the same conceptual interface rather than translating one incompatible interface into another.

Code Example

public class AuthorizedReportService : IReportService
{
    private readonly IReportService _inner;
    private readonly IUserContext _user;

    public Task<Report> GetAsync(int id)
    {
        if (!_user.CanViewReports)
            throw new UnauthorizedAccessException();

        return _inner.GetAsync(id);
    }
}