Re: Passing Pointers -- where to delete them
On Mar 3, 7:29 pm, Ian Collins <ian-n...@hotmail.com> wrote:
James Kanze wrote:
On Mar 3, 7:24 am, Ian Collins <ian-n...@hotmail.com> wrote:
jason.cipri...@gmail.com wrote:
On Mar 3, 12:37 am, Arv <arvind.b...@gmail.com> wrote:
I got most things clarified now, but I still have a doubt
related to shared_ptr. When I use a singleton object, would
a shared_ptr help?
Not really, because:
Because when I use new inside the singleton's getInstance
method, I am not sure when to delete it, since it is a
static member, i am not sure putting the delete in the
destructor would help. Should I have another method called
resetInstance or something?
Well, if it's a singleton, why would you want to reset it? ;-)
Unit tests - you would want the object reset before each test.
In such cases, I'll use a separate process for each test. It's
a lot closer to the actual use case. But even then, unit tests
for singletons are somewhat difficult. Typically, the singleton
will look like a memory leak, which, of course, causes the test
to fail---you need to take special precautions to avoid this.
I guess that depends whether you allow your singletons to have
public constructors and destructors.
By definition, a singleton doesn't have public constructors or
destructors, at least as I understand the pattern. (At least as
I use and understand the word, singleton refers to a specific
pattern, and not to just any class which happens to be present
only once.) But that's not really the issue. My test harness
ensures that any memory allocated within the test has been freed
at the end of the test. If the first call to the instance()
function of the singleton is within the test, any memory
allocated by the creation of the singleton will appear as a leak
at the end of the test.
If the creation of the singleton is incidental to the
test---i.e. the test needs the singleton to run, but is not
testing the actual creation---then I'll just arrange to create
it before starting the tests. My test harness has special
options for this sort of thing. If the goal is to test the
instantiation process itself, on the other hand, I'll run each
test in a separate process (without memory leak checking, at
least during the creation of the singleton).
--
James Kanze (GABI Software) email:james.kanze@gmail.com
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