Re: handle deallocate memory on return
On Jun 30, 1:25 am, alessio211734 <alessio211...@yahoo.it> wrote:
I would like avoid to free memory every time that my function return.
I would like avoid to use goto c instruction to jump a code where I
call
EVP_PKEY_free(pkey_fsys);
EVP_PKEY_free(pkey_cert);
to free memory (openssl function)
My code:
[Snip]
Please suggest me a better solution.
C++ was written for \expressly this\ (among other things).
Destructors. Here's a quick example. Cleaner alternatives exist, such
as the scope guard header (google is your friend here), but this
example shows the "guts" of how it works:
if (!(EVP_PKEY_cmp_parameters(pkey_fsys,pkey_cert)))
{
struct KeyOwner
{ KeyOwner(key_type key_) : key(key_) {}
~KeyOwner() { EVP_PKEY_free(key); }
key_type key;
};
KeyOwner pkey_fsys_owner(pkey_fsys);
KeyOwner pkey_cert_owner(pkey_cert)
// lots of if - returns, want to free keys
// scope exited normally, want to free keys
}
The KeyOwner objects will be destroyed when the scope is exited iff
they are created as they are stack variables. When they are destroyed,
they will free their owned key. The scope guard header gives you a
general purpose class and macro which accomplishes the same thing.
Boost shared pointer has similar functionality, though it incurs some
overhead (shared and threadsafe) whereas the above has no overhead.
Also, the general purpose solution really only shines with C++0x
closures, though the scope guard macro ON_BLOCK_EXIT does pretty well
with C++03 binders, and better still with Boost lambda library.
Also, you may want to consider wrapping such resources in a class
whose destructor will free it, then you can simply use auto_ptr
instead of KeyGuard or more "general purpose" solutions.