Line Count with PowerShell

Starting to get the hang of PowerShell.  Today I wanted to quickly count the number of lines in some source code.   There's a simple implementation and then there's a better one.  In the end I settled on:

$count=0;gci . -i *.cs,*.cpp,*.h -r | %{$count += [System.IO.File]::ReadAllLines($_.FullName).Count};$count

Which is quick to type and fast enough for me, although as the links show you can butter it up and put it in a .ps1 file if you want too.

Puzzle Time!

Here's a little PowerShell test that I have to admit I had to get some help with.  Why does:

1,2,3 | %{$_}

Produce the output:

1
2
3

But this produces nothing:

$code={%{$_}}
1,2,3 | &$code

Remember, & executes a script block and % is just an alias for Foreach-Object.

Want the answer?

It's a question of scope.  In the second example &$code is equivalent to &{%{$_}}.  The extra {}'s puts $_ in a different script variable scope, one in which it has not been initialized.  To get things working again, you need to reattach it to the pipeline input, like so:

$code={$input | %{$_}}
1,2,3 | &$code