When it comes to some of our package features in ConceptShare we found it much easier to use a flag enumeration to test if a particular package had a given feature enabled such as SSL, custom branding, etc.

Flag enumerations behave very similar to a standard enumeration just that it allows usage of bitwise operations to “test” if a particular value is selected. Flag enumerations basically work off of the powers of 2. Below is a sample enumeration (C#.NET):

[System.Flags()]
public enum PFlags
{
    None = 0,
    SSL = 1,
    CustomBranding = 2,
    PaidAccount = 4,
    All = SSL | CustomBranding | PaidAccount
}

So you have the enumeration, let’s write a few little wrapper classes to make it easy to “Set” flags, and also “Check” flags.

public Boolean IsFlagSet(PFlags flags, PFlags flagItem)
{
    return ((flags & flagItem) == flagItem);
}
public PFlags SetFlagOn(PFlags flags, PFlags flagItem)
{
    return (flags | flagItem);
}
public PFlags SetFlagOff(PFlags flags, PFlags flagItem)
{
    if ((flags & flagItem) == flagItem)
        flags ^= flagItem;
    return flags;
}

That is all there is too it. You don’t have to use the helper functions and you can write the code inline but I find this easier as I sometimes forget which bit-wise operator I should be using. I won’t go into the theory of how flag enumerations work as there are many comprehensive articles available online. Below are some samples on how to use the functions.

// Enumeration with SSL & Custom Branding Set;
PFlags f = PFlags.SSL | PFlags.CustomBranding;
// Checks if SSL is enabled (returns true);
Boolean result = IsFlagSet(f, PFlags.SSL);
// Sets Custom Branding Off
f = SetFlagOff(f, PFlags.CustomBranding);

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