Using Custom Prompts for Mandatory Parameters

When you define mandatory parameters in PowerShell, the user gets prompted for the value if it is missing. The prompt uses the parameter name only as you can see when you run this code:

param
(
  [Parameter(Mandatory)]
  [string]
  $UserName

)

"You entered $Username"
 
UserName: tobi
You entered tobi 
 

To get more descriptive prompts, you can use more explicit variable names:

param
(
  [Parameter(Mandatory)]
  [string]
  ${Please provide a user name}

)

$username = ${Please provide a user name}
"You entered $Username"
 
Please provide a user name: tobi
You entered tobi  
 

Simply wrap the param() structure in a function to produce commands:

function New-CorporateUser
{
    param
    (
      [Parameter(Mandatory)]
      [string]
      ${Please provide a user name}
    )

    $username = ${Please provide a user name}
    "You entered $Username"
}
 
PS C:> New-CorporateUser
Cmdlet New-CorporateUser at command pipeline position 1
Supply values for the following parameters:
Please provide a user name: Tobi
You entered Tobi 
 

The flip side is that blanks and special characters in parameter names make it impossible to assign values via command line because parameters cannot be quoted:

 
PS C:> New-CorporateUser -Please  provide a user name
 

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