How would I convert this Delphi Set code to C#?

Question

I've got the following Delphi code that defines a set and then a simple if statement that checks if a passed value of the set type falls within certain values.

TOverwriteMode = (omNone, omDateAndSize, omDateOrSize, omDate, omSize, omForce);

...

if OverwriteMode in [omDateAndSize, omDateOrSize, omDate, omSize] then
begin
end;

I've converted it to C# using an enum, but the code for checking the value now consists of an if or statement which seems a bit long winded to me.

public enum FileOverwriteMode
{
    None,
    DateAndSize,
    DateOrSize,
    Date,
    Size,
    Force,
}

...

if ((overwriteMode == FileOverwriteMode.DateAndSize) || 
    (overwriteMode == FileOverwriteMode.DateOrSize) || 
    (overwriteMode == FileOverwriteMode.Date) || 
    (overwriteMode == FileOverwriteMode.Size))
{
}

Is there a way to simplify it using some kind of C# set equivalent?

Answer 1

You could try something like

FileOverwriteMode overwriteMode = FileOverwriteMode.DateAndSize;
if (new HashSet<FileOverwriteMode> 
    { 
        FileOverwriteMode.DateAndSize, 
        FileOverwriteMode.DateOrSize, 
        FileOverwriteMode.Date, 
        FileOverwriteMode.Size 
    }.Contains(overwriteMode))
{
}

Answer 2

Well, you can do:

private static readonly HashSet<FileOverWriteMode> ValidOverwriteModes
    = new HashSet<FileOverWriteMode>
{
    FileOverwriteMode.DateAndSize, FileOverwriteMode.DateOrSize,
    FileOverwriteMode.Date, FileOverwriteMode.Size,
};

...

if (ValidOverwriteModes.Contains(overwriteMode))
{
    // ...
}

(Rename ValidOverwriteModes depending on what the real meaning is.)

Answer 3

Jon's HashSet solution looks cleaner but here is one of the lightweight solutions:

[Flags]
public enum FileOverwriteMode
{
    None = 1,
    DateAndSize = 2,
    DateOrSize = 4,
    Date = 8,
    Size = 16,
    Force = 32,
}

and check it like:

// you might need to do some typecasting here and there
const int desiredMode = FileOverwriteMode.DateAndSize 
    | FileOverwriteMode.DateOrSize 
    | FileOverwriteMode.Size;

if(overwriteMode & desiredMode == desiredMode) 
{
}