Comments on blog.jamesjones.name: Generic Enum "Composed Of" Test

I agree with you on is that the application of thi...

2010-02-23T21:14:49.092-05:00

I agree with you on is that the application of this function is narrow. It's one of the first blog posts I've ever made so I cherry-picked a topic with a narrow scope thinking that people wouldn't criticize the usefulness of something that they don't plan on using or don't care about. But I digress...

When I say "strongly typed enum", I'm describing the difference between dealing directly with the enum in question verses the enum cast to the Enum class. The keyword "enum" vs. the class "Enum". You can see from the screen shot I posted that Anon's method doesn't compile when using Enum (the class).

Good observation that Microsoft will be offering a replacement to this function in .NET 4. I'll put a note at the top of my post to observe that this code snippet is obsolete. Thanks!

This application seems so narrow, I don't see ...

2010-02-23T17:49:00.438-05:00

This application seems so narrow, I don't see why you'd need a 30-line generic implementation to address the issue. I don't understand why you couldn't use the other commenter's simpler solution. Do you honestly have multiple enumerations whose values are used as bit flags, and whose underlying value types you don't know? Speaking of which, ideally you should be using the [Flags] attribute, which should also help simplify this.

Luckily, in .NET 4 you can use the Enum.HasFlag method and avoid jumping through even the hoop of the simple bitwise AND.

Also, what do you mean by "strongly typed enum"? C# enums are naturally strongly typed.

Mr. Anonymous, You are absolutely correct. I tota...

2010-02-21T13:18:40.563-05:00

Mr. Anonymous,

You are absolutely correct. I totally misrepresented the context that I was working in, where this function would be handy. That context was that I didn't have a strongly typed enum to work with. What I WAS working with was the "Enum" class, which you cannot perform bitwise operations on.

Thank you for pointing out my oversight. I'll update my post accordingly.

While this may work, there is a far more elegant s...

2010-02-19T15:21:23.027-05:00

While this may work, there is a far more elegant solution: just use bitwise operations. To test if Modify contains Read in the example above, you just need to write one line:

(FilePermission.Modify & FilePermission.Read) == FilePermission.Read

That line returns true since the logical AND operation between 0001 (Read) and 0011 (Modify) returns 0001 (Read).