How Do I format an 'if' conditional into a variable? - powershell

Question

I have a function where if a -Exception parameter is present, I need to use a different if statement. Is there a way I can put in if statement conditionals into a variable?
function Set-ErrorProvider
{
Param (
[Parameter(Mandatory = $true)]
[System.Windows.Forms.ErrorProvider]$Name,
[Parameter(Mandatory = $false)]
[System.Windows.Forms.Control[]]$Controls,
[Parameter(Mandatory = $false)]
[string]$TextBoxException,
[Parameter(Mandatory = $false)]
[ValidateSet("MiddleLeft")]
[string]$Alignment,
[Parameter(Mandatory = $false)]
[string]$Message,
[Parameter(Mandatory = $false)]
[int]$Padding,
[switch]$Clear
)
# Exceptions are written in the format of an if statement condition
# e.g. -and $TextBox -ne "TextBoxAction"
if ($PSBoundParameters.ContainsKey('$TextBoxException').Equals($false))
{
$TextboxIf = $Control.Text -eq $null -or $Control.Text.Trim().Length -eq 0
}
else
{
$TextboxIf = '$Control.Text -eq $null -or $Control.Text.Trim().Length -eq 0 $Exception'
}
I'm having trouble formatting the $TextboxIf variable because I want to use it as below:
if ($TextboxIf)
The $Exception variable will hold something like "-and $Textbox.Text -ne $null" (a custom exception).
Any ideas on how to format the if conditional for the $TextBoxIf variable?