Re: [boost] shared_ptr to self while in constructor

From: Jonathan Wakely (cow_at_[hidden])
Date: 2005-01-12 12:25:27

On Wed, Jan 12, 2005 at 09:11:43AM -0700, Dave wrote:

> A direct call to shared_from_this() does not work in a constructor.  Is
> there any way that I may obtain a shared_ptr to myself while under
> construction?

I don't think so - since shared_from_this() requires the object to already
be owned by another shared_ptr, which can't be possible if the object
hasn't been constructed yet.

When you create a shared_ptr from a raw pointer, shared_ptr's
constructor checks whether the pointee is of a type derived from
enable_shared_from_this and if so it initialises a weak_count in the
enable_shared_from_this base class.

Since you have not constructed your object yet you cannot have passed
its address to a shared_ptr yet, so the weak_count can't have been
initialised, so shared_from _this() will throw a bad_weak_ptr.

jon

-- 
"Everything is permitted."
	- Fyodor Dostoyevsky, 'The Brothers Karamazov'