new(nothrow not even from constructor)

From:
Virchanza <virtual@lavabit.com>
Newsgroups:
comp.lang.c++
Date:
Sun, 19 Dec 2010 03:55:48 -0800 (PST)
Message-ID:
<26e1b984-1b2a-4439-ba24-94a7f9990988@o14g2000yqe.googlegroups.com>
    I've been looking through the Dinkumware reference manual and I
can't find a form of "new" that doesn't throw any exceptions at all.

    I'm currently writing a program that uses the "new" operator to do
stuff like create thread objects and window objects. If a thread
object or window object can't be created, my program displays a
message box, something like "Creation of the Help dialog box failed".
Ideally it would be:

    Thread *const p = new(std::nothrow) Thread(my_entry_function,
JOINABLE);

    if (!p)
    {
        wxMessageBox("Can't create thread");
        return;
    }

The problem with this however, is that don't want any exceptions at
all to be thrown by the "new" operator. For instance, the following
"Hello World" program doesn't work:

#include <new>
#include <iostream>

class MyClass {
public:

    MyClass()
    {
        throw 5;
    }
};

int main()
{
    MyClass *p = new(std::nothrow) MyClass();

    std::cout << "Hello World!\n";
}

The "nothrow" only stops "new" from throwing a "bad_alloc" if the
memory allocation fails -- it doesn't suppress exceptions thrown from
the constructor of the object. (Or at least that's the GNU C++
behaviour).

Is the following my only option?

int main()
{
    MyClass *p;

    try { p = new MyClass(); } catch(...) { p = 0; }

    std::cout << "Hello World!\n";
}

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