James O'Neill's Blog

March 21, 2011

What’s in my PowerShell profile (2) edit

Filed under: How to,Powershell — jamesone111 @ 11:59 am

Carrying on with the theme of Useful Stuff For A PowerShell Profile, which I started with WhatHas, I want to show the edit command I added.
To begin with – in the betas releases – I was  a little bit annoyed and puzzled that there was no easy way to tell the PowerShell ISE to edit a file, but when I found there is a route to do so through the object-model I added an edit function to my profile. A very similar function is in the release version with PSEdit, I’ve kept mine which looks like this:

function edit {
   param ([parameter(ValueFromPipelineByPropertyName=$true)] 
          [Alias("FullName","FileName")]$Path
   )
   process {
 
     if (test-path $path) {
           Resolve-path $path -ErrorAction "silentlycontinue" | foreach-Object {
               if ($host.name -match "\sISE\s") {
             
     $psise.CurrentPowerShellTab.Files.add($_.path) | out-null }
            
  else {notepad.exe $_.path} }
         
 }
       else {write-warning "$path -- not found "}
   }
}

It only takes one parameter, which can come via the pipeline – enabling piping is a habit I’ve developed. I use a couple of PowerShell’s clever tricks with parameters – first, instead of using the whole piped object it can use a single named property of the object, and second, aliases let me invoke edit with –path or –fullname; that’s not a lot of use here – I can miss the name out completely and PowerShell knows which parameter I mean because there is only one. But the result of putting the two together is clever-squared: it says to PowerShell “if you find the object has a Path property, use it, if it doesn’t but has a FullName property use that, if it doesn’t have one of those but has FileName, use that” and so on.

A real-world use for this is I had some scripts which fetched a folder name from WMI and used PowerShell’s built-in Join-Path cmdlet to add a file name to it to create a parameter for another call to WMI. This worked against remote servers but I found that if the folder starts with a drive letter which exists on the remote server but not on the local machine , Join-path will produce an error, so I had to do the operation without Join-path.  I can use WhatHas Join-path to get  MatchInfo objects for each occurrence of Join-path. These objects have a Path property so loading all the affected scripts into the ISE editor is as simple as:
whatHas join-path | edit

Piping is the main place where my version scores over PSEdit  (the other being that it works in outside the ISE). The body of the function just has to open the requested file(s). Test-Path and Resolve-Path accept arrays, so I don’t need to any work to allow the function to be called as edit.\file1.ps1, .\file2.ps1.
If Test-Path says no valid name was passed, a warning is printed, but if it is valid  Resolve-Path is used to turn a partial name or wildcarded name into one or more paths.  If multiple names are passed and any IS valid, execution will reach Resolve-Path which will produce an error if any IS NOT valid – hence the use of –ErrorAction.
Armed with one or more valid, fully qualified paths, it’s a case of using the ISE’s object model to open the file: of course that only works in the ISE so the command falls back to notepad if the host name isn’t “Windows PowerShell ISE Host”

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