Re: Proper use of templated containers as class members
On Dec 5, 8:31 pm, Jeff Schwab <j...@schwabcenter.com> wrote:
Victor Bazarov wrote:
James Kanze wrote:
If you return a reference, it can only be to a "contained
object". Otherwise, how do you manage its lifetime.
...
And even if it is part of the object, the idea behind the
typedef combined with the accessor essentially represents
the abstraction which should tell the user of the class
*not* to rely on what the typedef resolves to.
As concrete examples, there are standard library instance
methods that return char const*, but do not necessarily store
instance data in contiguous, null-terminated arrays.
std::string::c_str() comes to mind.
Really. Do you know of an implementation of std::string which
doesn't store the data in contiguous, null-terminated arrays?
More generally, his function returned a reference. None of the
coding conventions I've seen have ever required a client side
delete of a reference. And unless otherwise stated, I think it
safe to say that the code doesn't depend on the presence of a
garbage collector.
It is also not hard to imagine a wrapper class around
std::time_t, having a c_str() method that delegates to
std::ctime. In these cases, it is common practice to use a
static (or user-provided) buffer that is potentially
overwritten on each call to the accessor method. The contract
explicitly states that the pointer is valid only for the
duration of a single statement, and is not re-entrant.
I think you're clutching at straws.
I also think that it isn't really very relevant. The OP asked
about typedef, not about interface design. I think we can
assume that his example was just that, a quickly thrown together
example, and not necessarily anything that reflected a real
design.
--
James Kanze (GABI Software) email:james.kanze@gmail.com
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