Re: Scope vs. point of construction for an object
Alan McKenney <alan_mckenney1@yahoo.com> writes:
(Cf.: "separate the declaration and construction of a local variable")
I've run into a situation with a class from a 3rd-party vendor, where:
1. There's no copy constructor or assignment operator.
2. The constructor may throw.
3. I need to use the object at various points in the code.
[snip]
The obvious approach -- use a pointer and "new" -- seems sort of ugly:
T *t_ptr = 0;
try { t_ptr = new T( /* long complicated list of constructor
arguments */ ); } catch (...) { /* stuff */ }
// use t_ptr
delete t_ptr; // don't forget to delete it
Is there a way that keeps the non-pointer syntax?
Even better would be if I could put it into an object.
You could use an array of char and placement new to construct the
object into the array storage. You could then use a flag checked in
the destructor of some object to call the destructor of your
object-in-an-array when it goes out of scope. IIRC, boost::optional
does this if you use the in_place() factory when constructing it:
boost::optional<T> t(boost::in_place<T>(constructor_args));
Anthony
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