Re: dynamically allocated buffers

From:

"Nevin \":-]\" Liber" <nevin@eviloverlord.com>

Newsgroups:

comp.lang.c++.moderated

Date:

27 Apr 2006 07:54:41 -0400

Message-ID:

<nevin-AF8D5C.18464726042006@news.isp.giganews.com>

In article <e2mcbn$5la$1@gavrilo.mtu.ru>, Raider <sraider@yandex.ru>
wrote:

void foo(char *ForceBuffer = NULL)
{
    char * Buffer;
    if (ForceBuffer) Buffer = ForceBuffer;
    else Buffer = new char[size];

    SomeCstyleFunctions(Buffer, ...);

    // Some C++ code here. May generate exeptions!

    if (!ForceBuffer) delete [] Buffer;
}

Choices are:
- auto_ptr<char, array_deleter<char> > // need to write array_deleter
that does delete[]
- boost::scoped_array<char> // need boost library
- vector<char> with resize()
- something else?

Which is the best?

Well, this kind of interface is fraught with peril, as it is trivial to
pass in a buffer that is the wrong size.

If I was stuck with this kind of interface, I'd probably write it as:

void foo(char* buffer = &std::vector<char>(SIZE)[0])
{
    if (!buffer) return foo();

    SomeCstyleFunctions(buffer, ...);

    // Some C++ code here. May generate exceptions!
}

This way the body of the function never has to worry about whether or
not to manage the buffer.

I'd still opt for a better calling interface, if at all possible.

--
  Nevin ":-)" Liber <mailto:nevin@eviloverlord.com> (773) 961-1620

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