Re: std::uncaught_exception
arindam.mukerjee@gmail.com wrote:
I was wondering if the following use of std::uncaught_exception is
advisable or not.
someclass::someclass( ... ) : ... all the initialization ...
{
struct scope_guard
{
someclass * that;
scope_guard( someclass * ptr )
{ that = ptr; }
~scope_guard()
{
if ( std::uncaught_exception() && that )
that->cleanUp(); // some method which
cleans up stuff
}
} __sg ( this );
....... Do all sorts of allocation .......
..... some of which could throw .....
// Don't want to do the following
// __sg.that = 0;
}
Unfortunately, there is a case in which this doesn't work. The problem
is that uncaught_exception() doesn't tell you whether the destructor is
executing due to stack unwinding, only if it is executing _during_ stack
unwinding. The difference is important if you create an object in a
destructor:
struct C
{
~C()
{
someclass s;
}
};
int main()
{
try
{
C c;
throw 1;
}
catch (...)
{}
}
cleanUp() will be called even if no exception is thrown in the someclass
constructor.
Yechezkel Mett
--
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p. 32, January 18, 1972