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  • Aradhana Khadanga thinks this is interesting:

Any class that overloads the function call operator (i.e., operator()) is a functor class. Objects created from such classes are known as function objects or functors. Most places in the STL that work with function objects work equally well with real functions, so I often use the term “function objects” to mean both C++ functions as well as true function objects.

From

Cover of Effective STL

Note

Function Objects