Re: [boost] std::map::find() wrapper

Subject: Re: [boost] std::map::find() wrapper
From: Stewart, Robert (Robert.Stewart_at_[hidden])
Date: 2011-05-04 16:14:26

Nevin Liber wrote:
> On 4 May 2011 13:24, Stewart, Robert <Robert.Stewart_at_[hidden]>
> wrote:
>
> > An interface that returns a reference doesn't have the same
> > problem.  The caller must take the address and then delete
> > it, which requires conscious misuse.
>
> So:
>
> delete foo;
>
> is not conscious misuse, but
>
> delete &foo;
>
> is conscious misuse?  Really?  I would say both are conscious
> misuse, since both require the user to do explicitly write
> code to do something.

Not quite.

foo *
f();

foo &
g();

void
h()
{
   foo * p = f();
   delete p; // not unreasonable
   foo & r = g();
   delete &r; // misuse
}

g()'s interface returns a reference and not a pointer.  That is a clear indication that g()'s caller does not own the memory.  By contrast, f() returns a pointer.  The caller is not unreasonable in thinking ownership might be transferred, particularly if local conventions indicate as much.

An interface that precludes the possibility for that sort of confusion is better.

_____
Rob Stewart                           robert.stewart_at_[hidden]
Software Engineer                     using std::disclaimer;
Dev Tools & Components
Susquehanna International Group, LLP  http://www.sig.com

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