Using a number as a switch parameter in PowerShell

Question

I am trying to build a cool "PowerShell command" (a script containing a global function that I could later use from the shell as a command) and I have a problem.

I am using parameters with param() and there is an option to use a switch parameter (one that does not get subsequent information but just used for an option later on - such as the -l at the Linux command ls).

The thing is that it works fine when the parameter name is a letter, but not with a number. It's strange since numbers could be defined as variables ($4).

What do I need to do?

It suppose to be like ping -6.

Ideas?

You don't need to do anything - because it can't be done. The PowerShell Language Specification §2.3.4 defines parameter names as starting with a letter — Mathias R. Jessen
– Mathias R. Jessen, Commented Oct 11, 2016 at 11:14
Kinda funny that this constraint still exists when they allow Unicode letters as the first character ... — Ansgar Wiechers
– Ansgar Wiechers, Commented Oct 11, 2016 at 11:53
What is the reason you need a number as the name for a variable? If you would like to write a function like ping -6, in PowerShell would make a function like Ping {param ([ValidateSet(4,6)][int]$IPVersion) ...} and you still can use this parameter as a boolean later on. — Johan de Haan
– Johan de Haan, Commented Oct 11, 2016 at 12:14
It is a function that connects netapp with powershell, by default to the clustered on tap but I wanted a "-7" switch to connect to a 7-mode netapp — Tomer Schweid
– Tomer Schweid, Commented Oct 11, 2016 at 12:26

2 revs · Accepted Answer · 2017-05-23 12:06:46Z

4

What you're asking is not possible, as Mathias pointed out in the comments.

From §2.3.4 of the language specification:

2.3.4 Parameters

Syntax:

command-parameter:
    dash   first-parameter-char   parameter-chars   colonopt
first-parameter-char:
    A Unicode character of classes Lu, Ll, Lt, Lm, or Lo
    _   (The underscore character U+005F)
    ?
…

The closest you get is something like this:

Param(
  [Parameter(Mandatory=$false)]
  [Switch]$_7
)

However, for your scenario something like this would be far more readable anyway:

Param(
  [Parameter(Mandatory=$false)]
  [ValidateSet(3,5,7)]
  [int]$Mode = 7
)

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