Question

I moved out the methods implementation from my class and caught the following error:

Use of class template requires template argument list

for a method which doesn’t require any template type at all… (for other methods everything is okay)

Class

template<class T>
class MutableQueue
{
public:
    bool empty() const;
    const T& front() const;
    void push(const T& element);
    T pop();

private:
    queue<T> queue;
    mutable boost::mutex mutex;
    boost::condition condition;
};

Wrong implementation

template<>   //template<class T> also incorrect
bool MutableQueue::empty() const
{
    scoped_lock lock(mutex);
    return queue.empty();
}

Answer 1

It should be:

template<class T>
bool MutableQueue<T>::empty() const
{
    scoped_lock lock(mutex);
    return queue.empty();
}

And if your code is that short, just inline it, as you can’t separate the implementation and header of a template class anyway.