.NET Enums [Flags] & Bitwise Design Question

infotechelg used Ask the Experts™
A hypothetical situation:

I have product features. These features are stored as BITWISE values in the database.

In my back-end code, I have a [Flags] enumerator that lists out all the features with its bitwise value assigned to each item in the enumerator.

This, obviously, gives us great benefit from a coding perspective, and, not to mention, faster I/O and fewer database records.

However, now I want to give someone the ability through a CMS interface, to add a new feature to the features table. Let's call it "Feature7"

So, "Feature7" gets added to the table with the next bit value assigned to it in the database. This is the 7th feature, so this will have a bit value of 64.

But now, the problem is that the [Flags] enum has to be manually updated to include the new feature and its new bit value. Which, doesn't really make the management of Features from CMS "automated"; there's still manual intervention needed from the developers.

So, my question is, using BITWISE, is there a way to make this fully automated without having to have code that generates a new DLL every time features are added to the table, like is suggested here:


Let me know if that makes sense.

Obviously, I know this doesn't need to be done using bits, so I don't need suggestions in that regard.

Thanks in advance!
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AndyAinscowFreelance programmer / Consultant

Using bits you could prefill the required enums, call them Feature7, Feature8....FeatureN.

However I usually don't use bitwise operators when the end user may need extra features.  I use a 1:n relation in two tables.  One table has the key value plus a user description.  The other table just stores the key along with the individual items.


Thanks for the reply, Andy. That's the problem: pre-filling the required enum values. I'm just wondering if anyone out there used BITWISE programming and was successful in automating processes.

Yeah, I know the 1:M database design is standard. But the appeal of bitwise is it's faster, it takes up less space, and it makes for really simple C# programming.
AndyAinscowFreelance programmer / Consultant

Don't forget using the 1:n pattern means you don't need to write any code (extremely simple to code), the DB handles data integrity via the relation between the tables.
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For my 2 cents worth, kind of share views with both of you.

InfoTech: I HEAVILY use flagged enums in numerous systems and databases for exactly the reasons you made.  Much less I/O on the db, fewer joins, and all around better performance.

But, as Andy points to, anytime where dynamic modifications are necessary (CMS), I have every single time gone back to 1:n in the db.  In my personal experience the code heaviness from attempting to make a dynamic enum both in general performance and code overhead outweighs the benefit of using an enum in the first place.


Thanks, Snarf.  That makes total sense.
AndyAinscowFreelance programmer / Consultant

Hmmm.  :-(

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