duck typing

From the so-called duck test: "If it looks like a duck, swims like a duck and quacks like a duck, then it probably is a duck."

duck typing (uncountable)

1. (computing, programming) A style of dynamic typing in which an object's current set of methods and properties determines the valid semantics, rather than its inheritance from a particular class or implementation of a specific interface.
   • 2006, Neal Ford, Scott Davis, No Fluff, Just Stuff Anthology: The 2006 Edition, page 16

     Ruby proponents call this duck typing:: if the variable responds to a message that asks it to quack like a duck and it quacks, it must be a duck. This is clearly different from the way that Java (and other strongly typed languages) work, ...

• duck typing on Wikipedia.Wikipedia