What are the most overused design examples? Provide better examples if you have them [closed]

Question

When given an example of refactoring, I'm tired of seeing a Data Access Layer with string literals for connection strings being replaced by IConnectionStringProvider.

eg:

public DataSet GetCustomers()
{
    string connectionString = "SQLClient;Blah;Blah";

    using(SqlConnection conn = new SqlConnection(connectionString))
    ...

to this

public DataSet GetCustomers()
{
    string coonectionString = connectionStringProvider.GetConnectionString();

    using(SqlConnection conn = new SqlConnection(connectionString))
    ...

In the Domain Driven Design world I'm tired of seeing the Domain be a Customer who has many Orders which also has many OrderLineItems. Please explain Aggregate Roots using something a bit more interesting please!

Or am I completely losing it and rehashing these simplistic is the best way to teach these ideas?

Ooh, and using shapes to explain inheritance...

What examples to you use to teach these concepts?

Answer 1

I'm tired of seeing functional-programming advocates show how "quicksort" can be implemented in one line in Haskell, OCaml, F#, Scheme, etc. The "quicksort" that they show is not really Quicksort, because it is not swapping elements in place, and is doing all sorts of list construction and garbage collection. Doing a real Quicksort in a functional language is really messy.

Makes me wonder what else they are lying about.