Re: casting (void *) to (class *)
* Jonathan Lee:
Hello all,
Can someone tell me what the best way is to cast a void* to a class
pointer? I'm currently using reinterpret_cast<ClassName *>
(myvoidpointer) and I'd prefer not to. But dynamic_cast<> complains
that void* isn't a class pointer. And static_cast<> doesn't seem right
either... I'd like run time checking. Of course, if reinterpret_cast
is the only way, I'll live with it.
I suggest doing the opposite of how you obtained the void* in the first place;
that seems logical.
But better, don't use void* pointers (except for the special case of identifying
objects in e.g. a hash table, in which case you should make sure to have
pointers to complete objects, e.g. obtained by dynamic_cast to void*).
However, void* may be practically necessary in the context of a C code callback.
For context, it's for a "thread" class with pthreads backing it. I
know that the void* was originally a pointer to the class and it is
merely being restored to the correct type (it's just the _this_
pointer being mangled by pthread_create).
There is a good chance that the original pointer was just implicitly converted
to void*, in which case the conversion was equivalent to a static_cast, which is
then what you should do to get back the original.
But consider using Boost threads.
AFAIK they're based on pthreads, but offering a more type safe C++ interface,
and in addition, will be part of C++0x so using them is preparing for the future...
Cheers & hth.,
- Alf
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