On Sep 28, 11:30 am, "Chris ( Val )" <chris...@gmail.com> wrote:
On Sep 28, 7:03 pm, James Kanze <james.ka...@gmail.com> wrote:
[...]
But you still don't have an object. You can use function try
blocks to remap the exception, or to treat it as a fatal error
(e.g. by calling abort or exit), but you cannot return normally
from the constructor, and the object that was being constructed
will not exist.
I have produced a crude example that will attempt to
prove otherwise:
# include <iostream>
# include <string>
# include <exception>
struct DataSource {
DataSource( std::string ds )
{
if( ds != "Oracle.driver.foo" )
throw "Could not connect to database";
}
};
class Base
{
private:
DataSource Ds;
public:
Base( std::string );
~Base() { std::cout << "Destructing now...\n"; }
void Print()
{ std::cout << "I am still alive - Please try again.\n"; }
};
Base::Base( std::string ds )
try // function-try block
: Ds( ds ) {}
catch( const char* msg ) {
std::cout << "Exception Caught: \"" << msg << "\"" << '\n';
throw std::exception();
}
int main()
{
Base* B;
try {
B = new Base( "Oracle.driver.bar" );
}
catch( const std::exception& e )
{
B->Print();
This is undefined behavior, since it accesses an uninitialized
pointer. If you get here, the assign in the try block has never
occured (and there is no Base object).
delete B;
}
std::cin.get();
return 0;
}
I am interested to hear your, and the groups
thoughts on the validity of such a construct.
Totally invalide.
totally wrong. I thought about it after I
a new object in the catch block. It was late