From Basics to Binary: Supercharge your PowerShell enums

Ready to level up your PowerShell enum game? Discover how [Flags()] transforms simple enums into powerful binary combinations, allowing you to manage multiple settings with elegant precision perfect for feature flags, permission systems, and configuration management.

Tips by Tobias & Aleksandar:

Using enums

Simple enums define a list of allowed values, and the user can pick exactly one. When enums are defined as a flag array, then the user can pick more than one value:

[Flags()]enum Features{ BootLog RealTimeProtection Firewall PhysicalAccess Leash}[Features]$myFeatures = 'Firewall', 'Leash'$myFeatures

By adding the [Flags()] attribute to the enum, each enum entry now gets its own unique bit value, thus the user can combine as many enum items as needed. The type [Enum] can shed some light into this. Here it lists the defined enum names:

• PS C:\> [Enum]::GetNames([Features])

Next, it shows the assigned true numeric values:

• PS C:\> [Enum]::GetNames([Features]) | ForEach-Object { '{0} = {1}' -f $_, ([Features]::$_ -as [int])}

When you assign multiple values, bit values are added:

• PS C:\> [Features]$myFeatures = 'Firewall', 'Leash'PS C:\> $myFeaturesFirewall, Leash PS C:\> $myFeatures.value__

There is just one problem: the assigned numbers are consecutive and thus ambiguous PhysicalAccess has ID 3, but RealTimeProtection+Firewall also adds to 3.

When you use [Flags()], you also need to manually assign unique values to the enum items:

[Flags()]enum Features{ BootLog = 1 RealTimeProtection = 2 Firewall = 4 PhysicalAccess = 8 Leash = 16}

Now each item has a unique ID:

• PS C:\> [Enum]::GetNames([Features]) | ForEach-Object {'{0} = {1}' -f $_, ([Features]::$_ -as [int])}

Now, with unique IDs, you can use enums like any other numbers to do binary arithmetic:

• PS C:\> [Features]'Bootlog,Leash'BootLog, LeashPS C:\> [Features]'Bootlog,Leash' -as [int]

Use the "+=" operator to add an element, and "-=" to remove it:

• PS C:\> [Features]$features = 'Bootlog'PS C:\> $features += 'Leash'PS C:\> $features += 'Firewall'PS C:\> $featuresBootLog, Firewall, LeashPS C:\> $features -= 'Leash'PS C:\> $featuresBootLog, Firewall

Likewise, when testing whether a given value is present in such a list, use binary operators like -band and -bor:

• PS C:\> $featuresBootLog, FirewallPS C:\> ($features -band 'Firewall') -eq 'Firewall'TruePS C:\> ($features -band 'Leash') -eq 'Leash'False

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Related links

• Using enumerations in PowerShell part 1 is here
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