std::unique pointer and custom lambda deleter error

Question

I am trying to use a std::unique_pointer and supply a custom lambda deleter with it, but I am getting syntax error:

cannot convert from 'wmain::<lambda_0f8f736f48c52ca6fa24492e7c0c1ec0>' to 'const std::default_delete<_Ty>'

with the following simple, minimal code:

#include <memory>

class TestClass
{
};

typedef std::unique_ptr<TestClass> TestClassPtr;


int _tmain(int argc, _TCHAR* argv[])
{
    TestClassPtr testPtr(new TestClass(), [](TestClass* w){ delete w;});

    return 0;
}

Is this the wrong way to supply a lambda deleter to a smart pointer?

Answer 1

The deleter must be part of the unique_ptr's type.

typedef std::unique_ptr<TestClass, void(*)(TestClass *)> TestClassPtr;

Your code should work after you make this change. Also, I'm assuming you're going to do something other than simply call delete on the pointer within the deleter. If not, there's no need to supply a custom deleter.