I've never agreed with that. Without a good definition of what exactly it means to "look and act like a Card", large projects can easily get several slightly different definitions of what a Card is like, and nobody knows exactly which methods to use where (so what exactly do I need to implement so my class is a "file-like object"?). Horrible.
I call it smurf typing. If it smurfs like a smurf, smurfs like a smurf and possibly smurfs like a smurf, we consider it a smurf. Good luck with that information.
I call it smurf typing. If it smurfs like a smurf, smurfs like a smurf and possibly smurfs like a smurf, we consider it a smurf. Good luck with that information.