How-to: Overload the C++ function operator()

I’m working my way through the first few chapters of James Reinders’ Intel Threading Building Blocks book, and its a little bit hard going. As much as I’m enjoying the mental exercise of thinking in parallel, when it actually comes to the coding they use a lot of function operator (i.e. operator()) overloading, and I’m not so familiar with it. As much as I’ve overloaded operators before so you could, for example, add two Fruit objects together and get their weight, or multiply an Employee->monthlySalary by 12 to get their yearly wage, I’d never overloaded the function operator itself, so wasn’t sure what was really going on in the code.

To fix this, I’ve knocked together a super-simple example to show how it works:

Which gives the output:

So, that’s how it works. Straight forward enough.

Another example, taken from the Function object wikipedia page:

Counting from 10 to 20 has never been funner =D

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