What the Heck is an ENUM?

re: What the Heck is an ENUM?

applepwc — Mon, 15 Dec 2008 08:48:23 GMT

Thanks.

I konw what is ENUM type(just a set of constants).I just wonder why the name is [System.Environment+SpecialFolder] (in PS)but not [System.Environment.SpecialFolder](in C#).

again,look this:

http://blogs.msdn.com/powershell/archive/2007/01/23/how-to-create-enum-in-powershell.aspx

PS > New-Enum my.color blue red yellow

PS > [my.color]::blue

PS > [my+color]::blue

Unable to find type [my+color].....

#==========================

All .net ENUM type need "+" instead of "." in PS

PS C:\test> [ActivationContext.ContextForm]

Unable to find type [ActivationContext.ContextForm]: make sure that the assembl

y containing this type is loaded.

At line:1 char:31

+ [ActivationContext.ContextForm] <<<<

PS C:\test> [ActivationContext+ContextForm]

IsPublic IsSerial Name BaseType

-------- -------- ---- --------

False True ContextForm System.Enum

re: What the Heck is an ENUM?

tfl — Mon, 15 Dec 2008 15:34:26 GMT

There are a bunch of PowerShell script samples up on MSDN that demonstrate some of the many hundreds of ENUMs available inside .NET.

To view samples, take a look at http://msdn.microsoft.com/en-us/library/tags-cloud.aspx?tag=powershell+enum

Getting valid values for a enum

Ronald S Woan — Tue, 16 Dec 2008 02:19:39 GMT

This is probably better than throwing an error to list valid values for an enum:

[system.enum]::getnames([System.Environment+SpecialFolder])

re: What the Heck is an ENUM?

Stranger — Wed, 17 Dec 2008 11:52:37 GMT

@applepwc In short the "+" in [System.Environment+SpecialFolder] distinguishes a namespace from a nested type. [System.Environment] is the typename of the Environment class. System is the namespace, Environment the class name. The +SpecialFolder means that SpecialFolder is a type defined _within_ the Environment class.

Compare this with c#:

namespace System

{

class Environment

{

// enum defined within Environment class!

enum SpecialFolder {...}

}

// => Type in PS: [System.Environment+SpecialFolder]

Now compare this with a SpecialFolder enum defined in a System.Environment namespace:

namespace System.Environment

{

// enum defined within System.Environment namespace!

enum SpecialFolder {...}

}

// => Type in PS: [System.Environment.SpecialFolder]

hth

re: What the Heck is an ENUM?

applepwc — Thu, 18 Dec 2008 04:16:14 GMT

@Stranger:

thanks for your clarification.

re: What the Heck is an ENUM?

Luke Breuer — Fri, 19 Dec 2008 23:18:49 GMT

It would be nice if Get-Help were to specifically list enum values. Or is there a way to reflect upon a cmdlet and find the types of its parameters, and then use the static method on System.Enum to pull the values? I would rather not have to inject strings into Get-Help contents, but you PowerShell folks haven't seem to have thought of this (or if you have, it is not clear to the public).