"Richard Maher" <maher_rj@hotspamnotmail.com> wrote in message
news:gr45pi$hsf$1@news-01.bur.connect.com.au...
If when an object's constructor throws an exception that object has
not in
fact been intantiated, then what happens to the bits/objects/variables
that
were initialized/instantiated before the exception was thrown?
For example, if I open a file, or connect a socket while constructing an
object and then throw an exception before the constructor/instantiation
completes, then what happens to the file or socket connections that were
successfully instantiated?
a) Garbage Collected in the fullness of time as they're no longer
referenced?
b) Destroyed, and o/ride finalize() method that's called immediately?
c) It's considered extremely bad form to do this in a constructor.
Have an
init() method instead?
Who considers it bad form for a constructor to throw an exception? I can
think of at least two reasons why a constructor might throw an exception:
1. Bad parameters
2. Inability to allocate a necessary resource (memory, database, socket,
file, etc.)
I think it is better that the constructor throw an exception, letting
you know immediately that instance creation failed, vs. creating a
zombie instance, requiring that you explicitly check it for validity,
and all the merry mixups that occur when you forget. An exception is
harder to forget, and more explicit, IMHO.
is necessary than throwing the exception. As you explain it, then