Arena Allocator, DTOR and Embedded Preallocated Buffer

// arena_unitest.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include "arena_allocator.h"


struct Thing {};


// constructing arena usage
void constructing_arena()
{
	{
		// allocate and construct a Thing
		MyArena<256> arena;
		Thing* thing = new (arena) Thing;
	}

	{
		// allocate dynamic array of integers
		int n = 10;
		MyArena<256> arena;
		int* arr = new (arena) int [n];
	}

	{
		// allocate big dynamic array
		MyArena<256> arena;
		double* arr = new (arena) double [1024*1024];   // Arena propagates this allocation to heap
	}
}


// constructing arena usage
void allocating_objects()
{
	{
		// allocate and construct a Thing
		MyArena<256> arena;
		Thing* thing = new (arena) Thing;
	}

	{
		// allocate dynamic array of integers
		int n = 10;
		MyArena<256> arena;
		int* arr = new (arena) int [n];
	}

	{
		// allocate big dynamic array
		MyArena<256> arena;
		double* arr = new (arena) double [1024*1024];   // Arena propagates this allocation to heap
	}
}


// constructing arena usage
void destroying_objects()
{
	{
		// register Thing's DTOR
		MyArena<256> arena;
		Thing* thing = new (arena) Thing;
		arena.DTOR(thing);            // DTOR will be called when arena goes out of scope
	}

	{
		// register array of DTORs
		int n = 10;
		MyArena<256> arena;
		Thing* things = new (arena) Thing [n];
		arena.DTOR(things, n);        // DTORs will be called when arena goes out of scope
	}
}


// is operator new [] ever called ?
#if 0
inline
	void* operator new [] (size_t size, Arena& arena)
{
	return
		arena.alloc(size);
}
#endif


struct Obj
{
	virtual ~Obj()	{;}
};


int main(int argc, char* argv[])
{
	MyArena<256> arena;
	int* pi = new (arena) int [10];
	Obj* po = new (arena) Obj [10];

	unitest::arena_usecases();

	constructing_arena();
	allocating_objects();
	destroying_objects();

	return 0;
}