Re: new(nothrow not even from constructor)

From:
Virchanza <virtual@lavabit.com>
Newsgroups:
comp.lang.c++
Date:
Sun, 19 Dec 2010 15:43:47 -0800 (PST)
Message-ID:
<71685bdd-92c4-4d20-bb8b-957c32851fa2@t35g2000yqj.googlegroups.com>
On Dec 19, 12:14 pm, "Bo Persson" <b...@gmb.dk> wrote:

Another thing to consider is that if "new" or "MyClass" throws because
of lack of resources, what are the odds that wxMessageBox will work at
that point? Isn't that trying to create a window telling you that
creating a window just failed?!


    Some of the objects I create are quite complicated in their
construction. For instance, if I create a thread object for sniffing a
network interface, it could fail for all sorts of reasons... lack of
memory, inability to open the network interface. If creation of the
object fails, I want to handle it gracefully without killing my
program.

Here's what I've resorted to doing:

#define NEW_NULL_FAIL(p,x) \
do \
{ \
    try \
    { \
        p = new(std::nothrow) x; \
    } \
    catch (...) \
    { \
        p = 0; \
    } \
} while (0)

So now my code is something like:

    Thread *p;

    NEW_NULL_FAIL(p, Thread(entry_func,JOINABLE));

    if (!p)
    {
        wxMessageBox(...
        return;
    }

    ContinueOn();

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