Build Your Own PowerShell Cmdlet: Part 4 of 9

re: Build Your Own PowerShell Cmdlet: Part 4 of 9

Sean Kearney (The Energized Tech) — Wed, 03 Oct 2012 18:49:13 GMT

I believe that all picks up tomorrow when "Begin, Process and End" blocks are used. You'll find this really useful when you read the entire series end to end. Almost like a Chapter from a book :)

re: Build Your Own PowerShell Cmdlet: Part 4 of 9

PoSHV — Tue, 02 Oct 2012 18:26:20 GMT

I think i have same problem as Morimu36. No matter what parameters i give, it keep saying file already exists :(

re: Build Your Own PowerShell Cmdlet: Part 4 of 9

Morimur36 — Tue, 02 Oct 2012 16:10:36 GMT

So I'm having an issue (probably user-related) but whenever I change the Parameter for the folder to an array I have a syntax issue on my file path. In other words, if I modify this line:

[STRING]$Folder="C:\PowerShell",

To become this line:

[STRING[]]$Folder="C:\PowerShell",

Whenever I call the function, it responds with this:

_______________________________________________________________________________________________

PS I:\> ADD-LOGFILE

ADD-LOGFILE : Error: C:\PowerShell\ Logfile _ 10-2-2012 _ 120659 .log exist

At line:1 char:12

+ ADD-LOGFILE <<<<

+ CategoryInfo : WriteError: (:) [Write-Error], WriteErrorException

+ FullyQualifiedErrorId : Microsoft.PowerShell.Commands.WriteErrorException,ADD-LOGFILE

C:\PowerShell

Logfile

10-2-2012

120659

.log

False

_______________________________________________________________________________________________

Any ideas on what I've managed to do wrong? It works as expected without that one change. To make sure I had things correct I also went back and copy/pasted.

re: Build Your Own PowerShell Cmdlet: Part 4 of 9

K_Schulte — Tue, 02 Oct 2012 13:56:23 GMT

@PoSHV: You could well add this line of code after the "param" statement. It could act as the complete body of the function.

@Sean: Batchman is back!!!

Hi my friend, Sean!

Good to "see" you again!!!

I read through the first part of your series of blog entries here and just wanted to say "Hi!" to you :-))

Well ... not only ... I have to admit ...

Your explanation of the "DefaultParameterSetName" is quite ... let's say "hard to understand" ...

You don't need a DefaultParameterSetName here at all and there is no parameter daclaration like:

param(

[Parameter(ParameterSetName="Folder")]

[STRING]$Folder="C:\PowerShell",

...

)

So there is no real effect of introducing a "DefaultParamterSet" here.

But it might be too difficult to explain the reason of introducing this default.

Anyway an example might help:

If I got i right, this statement has been added to PS V2.0 in order to be able to allow for a "most appropriate behaviour" in case of ambiguous unnamed parameters!

If we have:

function f {

# [CmdletBinding(DefaultParametersetName="Set2")]

param(

[Parameter(ParameterSetName="Set1",Position=0)] [string] $s,

[Parameter(ParameterSetName="Set2",Position=0)] [string] $i

)

$PsCmdlet.ParameterSetName

}

the call:

f 1

will result in an error, because PS does't know if we want $s or $i to be set unless we use named parameters!

The way out is to specify a default solution to this conflict:

And if we uncomment the second line, it works because of the DefaultParameterSet

Way cool ...

Klaus.

re: Build Your Own PowerShell Cmdlet: Part 4 of 9

PoSHV — Tue, 02 Oct 2012 12:50:48 GMT

Where exactly in the script "If ($PSCmdlet.ShouldProcess("Creation of Logfile $Logfilename Successful")) { NEW-ITEM –Type File -path $Logfilename -Force | OUT-NULL } " should be added?