I have a string like this:
"CleanUp -All"
How do you convert it into a callable function in PowerShell including the switch?
I tried calling "&" in front of the entire string.
I tried splitting up the string into parts and calling them together.
I used the "&" to call the first part of the string "CleanUp" into a function but I don't know how to convert the switch parameter to use it.
A string containing a command line - i.e. a command name/path plus arguments - can not be invoked with &, the call operator - & only operates solely on a command name/path, requiring any arguments to be passed separately - see this answer.
While you can use Invoke-Expression to execute a string containing an entire command line:
Use of Invoke-Expression (iex) is best avoided in general.
Such an invocation (iex 'CleanUp -All') does not act like a function in two respects:
It requires renewed parsing of the command line in repeat invocations.
It doesn't accept additional arguments - unless you use string interpolation to make them part of the string passed to iex.
The better solution is to create a script block, which is only parsed once and can be re-invoked on demand with & (or, if the intent is to directly execute in the caller's scope, with ., the dot-sourcing operator):
# Create a script block from the command-line string, which you can
# invoke on demand with & or . - e.g.: & $sb
$sb = [scriptblock]::Create('CleanUp -All')
If you additionally want to support pass-through arguments, append @args to the command-line string:
$sb = [scriptblock]::Create('CleanUp -All' + ' @args')
If you want to create an actual, named function, Invoke-Expression is the simplest solution, after all:
# Define function 'Foo' which calls CleanUp -All with pass-through
# arguments, if any.
iex ('function Foo { ' + 'CleanUp -All' + ' @args }')