C++ vector::erase complains about overload resolution & deleted operator '=='

Question

I am on C++ using std::vector to store a list of class objects using vector::push_back.

My add function accepts the base class type so that the same method can be used across.

Add(MyBaseClass object) {
  my_vector.push_back(object)
}

I have remove function to remove it by per item added

Remove(MyBaseClass object) {
  my_vector.erase(std::remove(my_vector.begin(), my_vector.end(), object), my_vector.end());
}

The add works fine but my Remove method gives following error:

overload resolution selected deleted operator '=='
            if (!(*__i == __value_))
              ~~~~ ^  ~~~~~~~~

I picked up the vector::erase code from here. What is wrong with my way of erasing an item? Are there any other preferable ways to erase by item?

nope. Do I need to have one defined ? shouldn't the default provided work ? — TheWaterProgrammer, Jan 16 '17 at 13:05
It sounds like you're expecting that to work with subclasses of `MyBaseClass`. It doesn't; read about "object slicing". — molbdnilo, Jan 16 '17 at 13:05
@SegmentationFault There is no default provided `operator==` for classes. — Holt, Jan 16 '17 at 13:05
There is no default provided one. If you want it you need to define it. — NathanOliver, Jan 16 '17 at 13:05
what if I am adding `std::functions` ? for example to implement callbacks, I want to have a list callbacks & remove each at will — TheWaterProgrammer, Jan 16 '17 at 13:13

score 3 · Answer 1 · answered Jan 16 '17 at 13:07

3

The Multipass guarantee of the ForwardIterator requirement for remove to work on std::vector specifies that MyBaseClass must implement operator==.

Your class doesn't appear to implement this, and compilation therefore fails.

answered Jan 16 '17 at 13:07

Bathsheba

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ok. let me try to define an `==` operator in my base class & check – TheWaterProgrammer Jan 16 '17 at 13:10
what if I am adding `std::functions` ? for example to implement callbacks, I want to have a list callbacks & remove each at will – TheWaterProgrammer Jan 16 '17 at 13:13

C++ vector::erase complains about overload resolution & deleted operator '=='

1 Answers1