Peering into script modules

Sometimes it’s handy to access internal elements of script modules. For instance you may be using a 3rd party module in your application and would like to see the internal state for debugging purposes.

This can be accomplished with the invoke operator (&) which allows you to access a modules session state:

& $module {script block}

The script block is executed in the context of the module.

Create a script module that exports nothing:

[string] $foo = "IamFoo"

function Hidden($zarg) {
    "$zarg was passed to me"
}

Export-ModuleMember -Function @()

Save to a file ‘NoExport.psm1’, import the module and assign to a variable:

PS> $m = import-module .\NoExport.psm1 -passthru

PS>& $m {Hidden 'bar'}
bar was passed to me

Likewise, we can also retrieve and set the module variable $foo:

PS>& $m {$foo}
IamFoo
PS>& $m {$script:foo = 'NewFoo'}
PS>& $m {$foo}
NewFoo

Cheers,

Nigel Sharples [MSFT]