Using attributes to cache a method's return results in C#

Question

In webmethods, it is very simple to implement caching by annotating [WebMethod(CacheDuration...] attribute. Can we create something similar for non-webmethods, such as Static methods?

Any help/tip is appreciated.

Answer 1

There is no built in feature for achieving exactly what you want. You should use Httpruntime.Cache.

It's not a built in feature but you may achieve something like that using aspect oriented programming (AOP). Caching information using aspects.

In case you're interested Spring.NET provides AOP

Answer 2

Check this simple implementation of an attribute for caching using Post Sharp.

Answer 3

If you can't use AOP to get the job done you could try using this little class I put together.

public MyClass CachedInstance
{
    get { return _cachedInstance.Value; }
}
private static readonly Cached<MyClass> _cachedInstance = new Cached<MyClass>(() => new MyClass(), TimeSpan.FromMinutes(15));

public sealed class Cached<T>
{
    private readonly Func<T> _createValue;
    private readonly TimeSpan _cacheFor;
    private DateTime _createdAt;
    private T _value;


    public T Value
    {
        get
        {
            if (_createdAt == DateTime.MinValue || DateTime.Now - _createdAt > _cacheFor)
            {
                lock (this)
                {
                    if (_createdAt == DateTime.MinValue || DateTime.Now - _createdAt > _cacheFor)
                    {
                        _value = _createValue();
                        _createdAt = DateTime.Now;
                    }
                }
            }
            return _value;
        }
    }


    public Cached(Func<T> createValue, TimeSpan cacheFor)
    {
        if (createValue == null)
        {
            throw new ArgumentNullException("createValue");
        }
        _createValue = createValue;
        _cacheFor = cacheFor;
    }
}