Adding two functions?

I just browsed through "C# in Depth" and stumbled upon the following code:

Func<string> stringFunc = () => "";
Func<object> objectFunc = () => new object();
Func<object> combined = objectFunc + stringFunc;

I'm pretty sure that adding two functions is meaningless in mathematics, so why would any programmer want an overload of the binary operator+ for functions? This seems to be a perfect example of why overloading operators can do harm开发者_开发知识库 (and I generally support the idea of operator overloading).

1. What does it mean to add two functions in C#? (I'm a C# noob, so bear with me.)

2. Do you agree that it was a design mistake to overload operator+ here?

3. What would be a better syntactic to achieve whatever it is operator+ does here?

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Writing delegate1 + delegate2 will create a third delegate instance which combines the first two, calling all functions in both delegates.
It's primarily intended for events.

Documentation

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Adding two functions is perfectly meaningful in mathematics. When you take the view that functions are operators then the space of all such operators is a linear space (under certain conditions). This is a very productive standpoint that yields a lot of useful mathematical insight.

Of course, that's not what's happening here, but I wanted to put you right on the mathematical side of your question!