Calling parameters as a variable

Can something like this be made to work?

PS C:\> $string="-detailed"
PS C:\> get-help get-command $string
Get-Help : A parameter cannot be found that matches parameter name
'-detailed'.
At line:1 char:9
+ get-help <<<< get-command $string
PS C:\> get-help get-command "$string"
Get-Help : A parameter cannot be found that matches parameter name
'-detailed'.
At line:1 char:9
+ get-help <<<< get-command "$string"

Hi Marco,

> Can something like this be made to work?
>
> PS C:\> $string="-detailed"
> PS C:\> get-help get-command $string

Not sure why your version does not work, but this one does:

PS> $string="-detailed"
PS> invoke-expression "get-help get-command $string"

Or if you prefer aliases:

PS> iex "get-help get-command $string"

hth

Max

I'm presuming you want to do this to propagate a switch parameter in a
function? You could use invoke-expression however PowerShell has explicit
support for exactly this scenario. Switch parameters normally don't take
arguments but if the name is specified with a colon, then they do. This
allows you to "forward" a function switch parameter to a cmdlet switch
parameter. Here's an example:

function my-help ($topic, [switch] $noisy)
{
get-help $topic -detailed: $noisy
}

In this function, the function parameter $noisy is used to control
the -detailed: switch on get-help.

-bruce

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Windows PowerShell Technical Lead
Microsoft Corporation
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"Marco Shaw" <marco@Znbnet.nb.ca> wrote in message
news:OjX0dv0FHHA.4688@TK2MSFTNGP04.phx.gbl...
> Can something like this be made to work?
>
> PS C:\> $string="-detailed"
> PS C:\> get-help get-command $string
> Get-Help : A parameter cannot be found that matches parameter name
> '-detailed'.
> At line:1 char:9
> + get-help <<<< get-command $string
> PS C:\> get-help get-command "$string"
> Get-Help : A parameter cannot be found that matches parameter name
> '-detailed'.
> At line:1 char:9
> + get-help <<<< get-command "$string"
>

"Bruce Payette [MSFT]" <brucepay@microsoft.com> wrote in message
news:eGWUoa2FHHA.3468@TK2MSFTNGP04.phx.gbl...
> I'm presuming you want to do this to propagate a switch parameter in a
> function? You could use invoke-expression however PowerShell has explicit
> support for exactly this scenario. Switch parameters normally don't take
> arguments but if the name is specified with a colon, then they do. This
> allows you to "forward" a function switch parameter to a cmdlet switch
> parameter. Here's an example:
>
> function my-help ($topic, [switch] $noisy)
> {
> get-help $topic -detailed: $noisy
> }
>
> In this function, the function parameter $noisy is used to control
> the -detailed: switch on get-help.

I've said it before and I'll say it again, that's one of those little
features of PoSh that I love.

--
Keith