{"id":73721,"date":"2015-08-27T00:01:00","date_gmt":"2015-08-27T00:01:00","guid":{"rendered":"https:\/\/blogs.technet.microsoft.com\/heyscriptingguy\/2015\/08\/27\/working-with-enums-in-powershell-5\/"},"modified":"2019-02-18T09:35:27","modified_gmt":"2019-02-18T16:35:27","slug":"working-with-enums-in-powershell-5","status":"publish","type":"post","link":"https:\/\/devblogs.microsoft.com\/scripting\/working-with-enums-in-powershell-5\/","title":{"rendered":"Working with Enums in PowerShell 5"},"content":{"rendered":"

Summary<\/b>: Ed Wilson, Microsoft Scripting Guy, talks about working with enums in Windows PowerShell 5.0 in Windows 10.<\/span><\/p>\n

Microsoft Scripting Guy, Ed Wilson, is here. Yesterday, I talked about the new stealth feature in Windows PowerShell 5.0 in Windows 10 that permits me to easily create an enum. Enums are great because they provide a concise way for me to check parameters, a great way to make code easier to read, and many other things.<\/p>\n

Note <\/b> Today's post continues New PowerShell 5 Feature: Enumerations<\/a>. You should read it prior to reading today's post.<\/p>\n

Awhile back, I wrote a function called Get-EnumValues<\/b>, which has since come to reside in my Windows PowerShell profile. I talk about this function in One of My Favorite PowerShell Functions<\/a>. What is cool about the function is that it accepts an enum, and then it returns an array of the enumeration names and the associated numeric values.<\/p>\n

This is an extremely powerful and helpful tool to have around when one is working with enums (whether self-created or one of the thousands of enums that reside in the .NET Framework). <\/p>\n

Here is the function:<\/p>\n

Function get-enumValues<\/p>\n

{<\/p>\n

 # get-enumValues -enum "System.Diagnostics.Eventing.Reader.StandardEventLevel"<\/p>\n

Param([string]$enum)<\/p>\n

$enumValues = @{}<\/p>\n

[enum]::getvalues([type]$enum) |<\/p>\n

ForEach-Object { <\/span><\/p>\n

$enumValues.add($_, $_.value__)<\/p>\n

}<\/p>\n

$enumValues<\/p>\n

}<\/p>\n

To use the function, I simply call Get-EnumValues<\/b> and specify the name of the enum in quotation marks:<\/p>\n

PS C:\\Users\\mredw> get-enumValues -enum "fruit"<\/p>\n

Name                     Value                                                   <\/p>\n

—-                           —–                                                   <\/p>\n

Kiwi                           31                                                      <\/p>\n

Pear                         30                                                       <\/p>\n

Apple                        29    <\/p>\n

One of the cool things I can use is the [enum]<\/b> type accelerator, and I can use that to display the values that are defined inside an enum. This is shown here:<\/p>\n

PS C:\\Users\\mredw> [enum]::GetValues([type]"fruit")<\/p>\n

Apple<\/p>\n

Pear<\/p>\n

Kiwi<\/p>\n

But it does not do what I would expect. I would expect to see the numeric values, not the enumeration names or properties. As shown here, when I reference a property via the enumeration, it simply displays the name again:<\/p>\n

PS C:\\Users\\mredw> [fruit]::Apple<\/p>\n

Apple<\/p>\n

The secret is knowing that there is a value__<\/b> property associated with each enumeration. When I call that, then I get the numeric value:<\/p>\n

PS C:\\Users\\mredw> [fruit]::Apple.value__<\/p>\n

29<\/p>\n

That is the “trick” that my Get-EnumValues<\/b> function uses to create the hash table it displays.<\/p>\n

Create new enum based on existing enum<\/h2>\n

One of the really cool things I can do with enums is use them to create new enums. To continue my example from yesterday, I can create more fruit. My original enum is shown here:<\/p>\n

Enum Fruit<\/p>\n

{<\/p>\n

 Apple = 29<\/p>\n

 Pear = 30<\/p>\n

 Kiwi = 31<\/p>\n

}<\/p>\n

Now I decide that I want to create more fruit. So I call my new enum MoreFruit<\/b>:<\/p>\n

Enum MoreFruit<\/p>\n

{<\/p>\n

}<\/p>\n

To combine a pear and an apple, I get a Papple. It is as simple as calling the pear enumeration and the apple enumeration and adding them together. This is shown here:<\/p>\n

Papple = [fruit]::Pear + [fruit]::Apple<\/p>\n

I can also combine a kiwi and an apple and get a Kapple:<\/p>\n

Kapple = [fruit]::Kiwi + [fruit]::Apple<\/p>\n

I imagine that I could combine a kiwi, a pear, and an apple and get a KaPapple, and this is what I do:<\/p>\n

KaPapple = [fruit]::Kiwi + [fruit]::Pear + [fruit]::Apple<\/p>\n

The complete script is shown here:<\/p>\n

Enum Fruit<\/p>\n

{<\/p>\n

 Apple = 29<\/p>\n

 Pear = 30<\/p>\n

 Kiwi = 31<\/p>\n

}<\/p>\n

Enum MoreFruit<\/p>\n

{<\/p>\n

 Papple = [fruit]::Pear + [fruit]::Apple<\/p>\n

 Kapple = [fruit]::Kiwi + [fruit]::Apple<\/p>\n

 KaPapple = [fruit]::Kiwi + [fruit]::Pear + [fruit]::Apple<\/p>\n

}<\/p>\n

When I run it, I can access the KaPapple from my MoreFruit<\/b> enum:<\/p>\n

PS C:\\Users\\mredw> [morefruit]::KaPapple<\/p>\n

KaPapple<\/p>\n

I can also see the numeric value of the KaPapple:<\/p>\n

PS C:\\Users\\mredw> [morefruit]::KaPapple.value__<\/p>\n

90<\/p>\n

I see that it added 29, 30, and 31 together to get 90. I can now use my Get-EnumValues<\/b> function to see what else is in my MoreFruit<\/b> enum. The output is shown here:<\/p>\n

\"Image<\/a><\/p>\n

That is all there is to using enums. Join me tomorrow when I will talk about more cool stuff.<\/p>\n

I invite you to follow me on Twitter<\/a> and Facebook<\/a>. If you have any questions, send email to me at scripter@microsoft.com<\/a>, or post your questions on the Official Scripting Guys Forum<\/a>. See you tomorrow. Until then, peace.<\/p>\n

Ed Wilson, Microsoft Scripting Guy<\/b> <\/span><\/p>\n","protected":false},"excerpt":{"rendered":"

Summary: Ed Wilson, Microsoft Scripting Guy, talks about working with enums in Windows PowerShell 5.0 in Windows 10. Microsoft Scripting Guy, Ed Wilson, is here. Yesterday, I talked about the new stealth feature in Windows PowerShell 5.0 in Windows 10 that permits me to easily create an enum. Enums are great because they provide a […]<\/p>\n","protected":false},"author":596,"featured_media":87096,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[1],"tags":[148,609,3,4,608,45],"class_list":["post-73721","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-scripting","tag-enum","tag-powershell-5","tag-scripting-guy","tag-scripting-techniques","tag-windows-10","tag-windows-powershell"],"acf":[],"blog_post_summary":"

Summary: Ed Wilson, Microsoft Scripting Guy, talks about working with enums in Windows PowerShell 5.0 in Windows 10. Microsoft Scripting Guy, Ed Wilson, is here. Yesterday, I talked about the new stealth feature in Windows PowerShell 5.0 in Windows 10 that permits me to easily create an enum. Enums are great because they provide a […]<\/p>\n","_links":{"self":[{"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/posts\/73721","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/users\/596"}],"replies":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/comments?post=73721"}],"version-history":[{"count":0,"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/posts\/73721\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/media\/87096"}],"wp:attachment":[{"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/media?parent=73721"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/categories?post=73721"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/tags?post=73721"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}