proper initialization

[bob]

Let's say that a class only allows proper initialization through
its constructor. Let's also say that you need a global variable of
that class,
but you can't initialize it at the beginning of the program.

What is the most practical solution?

 

[Alf P. Steinbach]

* (e-mail address removed):

Let's say that a class only allows proper initialization through
its constructor. Let's also say that you need a global variable of
that class,
but you can't initialize it at the beginning of the program.

What is the most practical solution?

At the risk of sounding like I'm bashing you, the most practical
solution is to _not_ use global variables, especially for a newbie.

See the FAQ about global variables.

Summary: they're evil.

 

[Victor Bazarov]

Let's say that a class only allows proper initialization through
its constructor. Let's also say that you need a global variable of
that class,
but you can't initialize it at the beginning of the program.

What is the most practical solution?

There is none. Global variables get initialised at the beginning, before
even 'main' is called. If you can't allow that, you're out of luck. Your
alternative is a singleton, which can be initialised at the first use (and
not necessarily at the beginning of the program), but then you're stuck
with using a function to obtain a pointer or a reference to that object:

class myPseudoGlobalVar {
...
public:
myPseudoGlobalVar(arguments);
void whatever();
};

static myPseudoGlobalVar& get_myPseudoGlobalVar() {
static myPseudoGlobalVar var(<initialise here>);
return var;
}

...
get_myPseudoGlobalVar().whatever();

V