Add operator

Question

I want to add `operator<<` to `std::vector`. This is the operator ``` std::vector& operator<<(std::vector& op, std::string str) { op.push_back(str); return op; } ``` Now I can add elements to vector this way: ``` std::vector vec; vec << "aaa" << "bbb" << "ccc"; ``` But the following code isn’t compiled since cant pass temporary object by reference. ``` std::vector() << "AAA" << "BBB"; ``` How can I change the code to add elements to temporary vectors too? I have a function which accepts `const std::vector&` argument so I want to pass to it a vector in one line.

Accepted Answer

You can't. The only way it could be achieved would be if your operator was a member of the vector. (For some reason member functions can be invoked on temporaries).

As a nonmember function though what you're after is impossible

Also it's not a very good idea to overload operators for STL types such as std::vector. I think what you're trying to accomplish is already present in boost assign library. I don't believe you can write it better than they have, so better use boost if you need this.

Add operator<< to std::vector

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