Re: [Boost-users] Problem with enable_shared_from_this and shared_ptr

Subject: Re: [Boost-users] Problem with enable_shared_from_this and shared_ptr
From: John Dlugosz (JDlugosz_at_[hidden])
Date: 2010-08-02 12:38:00

> Except that you lose the ability to write code like
> 
> T t;
> shared_ptr<T> tp(&t, &nop_deleter);
> 
> or simply code like
> 
> T t;
> 
> if you mandate that anything that inherits enable_shared_from_this
> should automagically conjure up a shared_ptr on demand.
> 
> --
> Lars Viklund | zao_at_[hidden]

My class doesn't have a custom-supplied deleter as a feature.  It was not necessary within the implementation to handle base/derived stuff; I guess I approached it in a different way.

A class that derives from the special base class is meant to be used as a pointer only.  It can't (portably) tell that the instance is not on the heap, and can't tell in general if you aggregated it.  Your point is that obtain-smart-pointer-from-this knows that no smart pointer was ever created and it should be an error instead?  

Certainly, I could have a form that means "give me a smart pointer if it's already in the system, but null if it's not", but I've never needed that.

--John






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