if(ptr) { /*ptr жив, можно работать*/ }

S>if(ptr) { /*ptr жив, можно работать*/ }
S>

struct shared_ptr
{
   int* ptr = nullptr;
};

int* raw_ptr = new int;
shared_ptr shared = { raw_ptr };

//...
delete raw_ptr;
raw_ptr = nullptr;

//...

if (shared.ptr) { /*shared.ptr жив, можно работать*/ }

Raw pointers are used whenever possible in the classes' public API. This simplifies exposing functions & classes to script, and is relatively safe, because SharedPtr & WeakPtr use intrusive reference counting.

https://urho3d.github.io/documentation/1.4/_conventions.html

somthing* ptr = new somthing;
...
somthing* rawptr = ptr;
...
delete ptr;
ptr = nullptr;
....
if(!rawptr) { /*оппа, указателя больше нет!*/ /* да неужели? */}

class Geometry
{
  ...
  Vector<SharedPtr<VertexBuffer> > vertexBuffers_;
  ...
};

bool Geometry::SetVertexBuffer(unsigned index, VertexBuffer* buffer)
{
    if (index >= vertexBuffers_.Size())
    {
        URHO3D_LOGERROR("Stream index out of bounds");
        return false;
    }

    vertexBuffers_[index] = buffer;
    return true;
}

bool Geometry::SetVertexBuffer(unsigned index, const SharedPtr<VertexBuffer>& buffer)
{
    if (index >= vertexBuffers_.Size())
    {
        URHO3D_LOGERROR("Stream index out of bounds");
        return false;
    }

    vertexBuffers_[index] = buffer;
    return true;
}

No C++ exceptions. Error return values (false / null pointer / dummy reference) are used instead.

struct mirror_ptr
{
   int*& ptr;
   mirror_ptr(int*& p) ptr(p){}
};

int* raw_ptr = new int;
shared_ptr<mirror_ptr> shared = make_shared<mirror_ptr<int>>(raw_ptr);

//...
delete raw_ptr;
raw_ptr = nullptr;

//...

if (shared->ptr) { /*raw_ptr жив, можно работать*/ }

When making your own work functions or threads, observe that the following things are unsafe and will result in undefined behavior and crashes, if done outside the main thread:

• Modifying scene or UI content
  
• Modifying GPU resources
  
• Executing script functions
  
• Pointing SharedPtr's or WeakPtr's to the same RefCounted object from multiple threads simultaneously

/// Reference count structure.
struct RefCount
{
    /// Reference count. If below zero, the object has been destroyed.
    int refs_;
    /// Weak reference count.
    int weakRefs_;
};