[worstspotgain]

> I just don't know what you mean by precisely wish to bar ownership

If foo() doesn't need to share ownership now but may need to later, declaring it as foo(const std::shared_ptr<bar> &) instead of foo(const bar &) allows this change without revising any prototypes. However, if we precisely wish to prohibit shared ownership by foo(), we can do so by declaring it as foo(const bar &).

> Prove it. In a single threaded program with scope based ownership

The incorrect assumption that you came to is that we were talking about stack variables. But anyways, here's an example that's both scope-based and single threaded:

   std::vector<std::shared_ptr<bar> > v;

with an algorithm that selectively adds our pointer to the vector one or more times, and another that duplicates and removes elements according to some ongoing criteria. The object gets deleted when no pointer instances are left in the vector.

In practice most code is multithreaded (not that it matters) and most shared_ptrs are held inside other objects (not that it makes a difference either.)

> Are you saying I'm wrong then saying the exact thing I just said?

I'm saying you misunderstood and now I clarified again. I'm at the troll-detection threshold, so this is my last clarification. Take care!

[CyberDildonics]

If foo() doesn't need to share ownership now but may need to later,

This doesn't make sense. Why would a function in a more narrow scope need to take or share ownership? The variable passed will persist before and after the function call.

The incorrect assumption that you came to is that we were talking about stack variables.

I don't know what this means here. I said scope, you are saying stack. If lifetime is being dictated purely by scope, you don't need shared_ptr, you can just use a unique_ptr at the correct scope.

But anyways, here's an example that's both scope-based and single threaded: std::vector<std::shared_ptr<bar> > v;

This isn't scope based lifetime, this is lifetime based on some other criteria than going out of scope. I will show you with what you wrote:

and another that duplicates and removes elements according to some ongoing criteria.