[boost] [pointer container] copyability

From: David Abrahams (dave_at_[hidden])
Date: 2005-04-26 11:08:00

I had this disagreement with Thorsten in Lillehammer (or was it
Oxford?) but he was unimpressed with my arguments.  I was wondering
what Boost as a whole would think:

My Thesis: the library should support copying and assignment of
  pointer containers using the usual copy/assignment syntax, rather
  than only allowing a copy via a clone() function.

Rationale: Not being able to copy and assign pointer containers is an
  arbitrary restriction that limits usefulness and expressivity.  The
  argument Thorsten gives against copyability is that the elements
  would have to be clone()d rather than copied, which is expensive
  because there's a dynamic allocation per element.  I don't get it;
  we don't arbitrarily prohibit copying of std::vector<std::string>
  even though that incurs a dynamic allocation per element.

Example: Consider std::pair<int,some_pointer_container>.  Almost
  nothing works. IIUC, it's not copyable, can't be initialized, and
  can't be clone()d.

-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com