How to validate WebParts attributes?

Question

For the follwing webpart attribute within PropertyEditorPart, is there any way to validate value entered by user?

[Personalizable(true),
WebBrowsable(true),
WebDisplayName("To Date: "),
WebDescription("Please enter To Date value.")]
public string ToDate
{
    get { return toDate; }
    set { toDate = value; }
}

This value rendered to TextBox, and I wonder if there a way to validate entered value?