Is there an equivalent of "this" in powershell?

Question

Basically I have this code:

$file = $web.GetFile("Pages/default.aspx")
$file.CheckOut()

and I was wondering if there is anyway to use a pipe and the powershell equivalent of this to rewrite it as:

$web.GetFile("Pages/default.aspx") | $this.CheckOut()

When I try this I get the error:

Expressions are only allowed as the first element of a pipeline.

I also tried using $_ instead of $this but got the same error.

Answer 1

Actually there is a $this in a few cases. You can create a ScriptProperty or ScriptMethod and attach it to an object, and $this will be the original object. You can then define these in types files (I'd recommend using the module EZOut, it makes life much easier) so that any time you see that type, you get that method.

For example:

$Web  | Add-Member ScriptMethod EditFile { $this.Checkout() }

Hope this helps

Answer 2

What you're looking for is $_ and it represents the current object in the pipeline. However you can only access $_ in a scriptblock of a command that takes pipeline input e.g.:

$web.GetFile("Pages/default.aspx") | Foreach-Object -Process {$_.Checkout()}

However there are aliases for the Foreach-Object cmdlet {Foreach and %} and -Process is the default parameter so this can be simplified to:

$web.GetFile("Pages/default.aspx") | Foreach  {$_.Checkout()}

One other point, the GetFile call appears to return a single file so in this case, the following would be the easiest way to go:

$web.GetFile("Pages/default.aspx").Checkout()

Of course, at this point you no longer have a variable containing the file object.