Comments on Johannes Hansen's Blog: Extension Types for easier (and strongly typed) At...

Thanks for sharing. It would be nice if C# allowed...

2010-10-29T15:57:16.408+02:00

Thanks for sharing.
It would be nice if C# allowed defining extension methods based on attributes. That way marker interfaces will be less needed.

THANKS MAN!, had been working on a litle project l...

2010-03-26T15:58:52.894+01:00

THANKS MAN!, had been working on a litle project like this to make attributeExt, but my brain like poped out :), now this , Good Job!

You may use this mixin :)

public st...

2008-10-29T08:28:00.000+01:00

You may use this mixin :)

public static bool IsAttributeDefined<T>(this ICustomAttributeProvider provider, bool inherit = true)
where T : Attribute
{
return provider.IsDefined(typeof(T), inherit);
}

public static T[] GetAttributes<T>(this ICustomAttributeProvider provider, bool inherit = true)
where T : Attribute
{
return provider.GetCustomAttributes(typeof(T), inherit) as T[];
}

public static T GetFirstAttribute<T>(this ICustomAttributeProvider provider, inherit = true)
where T : Attribute
{
return provider.GetAttributes<T>(inherit).FirstOrDefault();
}
}

P.S. some C# 4.0 code :)

And with that, I believe you've addressed the two ...

2008-10-20T14:16:00.000+02:00

And with that, I believe you've addressed the two most significant concerns of the subject matter. Thank you!

Performance of attributes vs. interfaces is very d...

2008-10-20T08:09:00.000+02:00

Performance of attributes vs. interfaces is very different and attribute comes out losing. In the tests I did, checking attributes were significantly slower than checking interfaces, sometimes up to 1000-2000 times slower!

But don't be too scared. For individual checks we are still speaking about 0.00002 secs. per attribute check, so it is not hurting your performance in any noticeable way as long as you aren't doing several thousand checks per second.

The thing to do is to judge it on a case by case basis and weigh the pros and cons whenever you need to employ a marker interface or attribute. Interfaces may be fast but has less flexibility than attributes.

Nice class! Have you considered or tested the perf...

2008-10-19T23:34:00.000+02:00

Nice class! Have you considered or tested the performance difference of the marker interface check vs checking for attributes using your code?