constructor throw problem

[mihai]

hi all,

I have a constructor witch at a given time it throws an exception,
and i have an static object of that class,
witch is initialized into the cpp file

the problem is that when the exception is raised the
the application crashes ...

have any idea how to bypass this problem ...

have a nice day,
mihai

 

[Mehturt]

hi all,

I have a constructor witch at a given time it throws an exception,
and i have an static object of that class,
witch is initialized into the cpp file

the problem is that when the exception is raised the
the application crashes ...

have any idea how to bypass this problem ...

have a nice day,
mihai

Can you post an example demonstrating your problem?

 

[mihai]

the code is someting like this ...

class A
{
public:
A()
{
if bad thing happens
throw exception;
}
....
};

class B
{
public:
static const A a;
};

// in B.cpp
const A B::a;

here is the problem ...
if A() throws the exception ... the application will creash...

 

[dj]

the code is someting like this ...

class A
{
public:
A()
{
if bad thing happens
throw exception;
}
...
};

class B
{
public:
static const A a;
};

// in B.cpp
const A B::a;

here is the problem ...
if A() throws the exception ... the application will creash...

Of course it will crash, since there is no way you can catch the
exception in global scope.

 

[mihai]

i understand this,

i am looking for a workaround ...



have a nice day ...

 

[Carlos Martinez]

Search for "Lazy initialization"

Basically is to defer the initialization of your object until you need it.
In your case, I'd use a pointer instead of your atribute

static A* a;

And initialize it with a NULL pointer.

You must give access to a through a getter method, returning a const
reference to a, instead of the pointer you have.

Protect your attribute inside the private section but let the getter in
the public section.

The code will be something like this:
class B {
static const A* a;
public:
static const A& getA() {
if(!a)
a=new A();
return *a;
}
};

// in B.cpp
const A* B::a=NULL;

 

[Rolf Magnus]

i understand this,

i am looking for a workaround ...

Well... don't throw an exception from the constructor.

 

[Bo Persson]

i understand this,

i am looking for a workaround ...



have a nice day ...

As you have probably already understood, there is just two ways to
solve this:

1. don't use a global or static variable
2. don't throw exceptions from the constructor


Your choice!


Bo Persson

 

[mihai]

thank you ...
i'll chose one of this ...

have a nice day,
mihai