static variables in abstract base classes

[pasa_1]

Are there any reasons one should avoid using static variables in
abstract base classes?

I was considering to the following:

#include <iostream>

using namespace std;

enum { SZ = 10 };

class AbstractBaseClass
{
protected:
static int a[SZ];
public:
AbstractBaseClass() { }
virtual void foo() const = 0;
static void bar(int i) { ++a; }
};

int AbstractBaseClass::a[SZ];

class Derived: public AbstractBaseClass
{
public:
Derived(): AbstractBaseClass() { }
void foo() const
{
int i = 0;
cout << "Derived::foo(): a[" << i << "]: " << a << endl;
}
};

 

[mlimber]

Are there any reasons one should avoid using static variables in
abstract base classes?

I was considering to the following:

#include <iostream>

using namespace std;

enum { SZ = 10 };

class AbstractBaseClass
{
protected:
static int a[SZ];
public:
AbstractBaseClass() { }
virtual void foo() const = 0;
static void bar(int i) { ++a; }
};

int AbstractBaseClass::a[SZ];

class Derived: public AbstractBaseClass
{
public:
Derived(): AbstractBaseClass() { }
void foo() const
{
int i = 0;
cout << "Derived::foo(): a[" << i << "]: " << a << endl;
}
};

There's no inherent problem with them, but you should initialize them
when you define them. Also consider using a container rather than a raw
array (http://www.parashift.com/c++-faq-lite/containers.html#faq-34.1).

Cheers! --M