Re: How to get rid of the new-initializer in a new-expression

From:

cbarron3@ix.netcom.com (Carl Barron)

Newsgroups:

comp.lang.c++.moderated

Date:

Sat, 16 Feb 2008 05:38:51 CST

Message-ID:

<1icdmpq.5ligxghb7id8N%cbarron3@ix.netcom.com>

Matthias Hofmann <hofmann@anvil-soft.com> wrote:

Hello everyone!

I have written a memory tracker using macros, and everything works fine
unless the new-expression contains a new-initializer. Please take a look at
the following example:

template <class T> T* TrackNew( T* ptr ) { return ptr; }

#define NEW( T ) TrackNew<T>( new T )

struct X
{
     X() {}
     X( int ) {}
};

int main()
{
     // Works fine.
     X* p1 = NEW( X );

     // Fails to compile.
     X* p2 = NEW( X( 2 ) );

     return 0;
}

The second use of the NEW macro expands to:

X* p2 = TrackNew<X( 2 )>( new X( 2 ) );

Obviously, this should be:

X* p2 = TrackNew<X>( new X( 2 ) );

Can anyone please tell me a portable way of getting rid of the
new-initializer in the new-expression? Like in the following pseudo code:

#define NEW( T ) TrackNew<REMOVE_NEW_INITIALIZER( T )>( new T )

well how about constructing it and passing as a const reference to a
creation template and then to Tracknew such as:

template <class X>
X * create_new(const X &x)
{
         return new X(x);
}

template <class T>
T *Tracknew( T *&x) { return x;}

#define NEW(X) Tracknew(create_new(X))

p1 = NEW(X()) ;
p2 = NEW(X(2));

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