Re: I wish exceptions would give you access to the stack trace
On Mar 10, 10:55 pm, Seungbeom Kim <musip...@bawi.org> wrote:
On 2011-03-10 11:48, Martin B. wrote:
But I accept that there really doesn't seem to be a good way to put this
into std C++, as (a) it's feasibility appears highly platform specific
and (b) the stack trace can only be reconstructed when debug symbols are
available, as otherwise the runtime costs will be far too high as you
would have to collect the stack info while building the stack (at each
function call) even if no exceptions were thrown.
That said, I still think that it would be a very interesting feature if
implementations could provide for a kind of exception stack trace for
developer analysis.
As an example, the GNU C Library does provide a stack trace,
not only in case of an exception, but whenever you
request.http://www.gnu.org/software/libc/manual/html_node/Backtraces.html
Collecting this information automatically when an exception is thrown
is another story, though. Moreover, not every exception thrown is an
"error" that needs debugging; it could merely be a communication between
different layers of the program, as long as it is caught at some layer.
This is, IMHO, the key. If there is an error which needs
debugging, C++ provides a far better mechanism than Java an
assertion failure, aborting the process. At least on Unix
platforms, this results in a core dump, which can be analysed by
the debugger. For any reasonable use of exceptions, the stack
trace is just extra overhead, and in the case of some
exceptions, like bad_alloc, could cause the program to crash,
rather than recovering gracefully. (How does Java handle this.
How can it create a stack trace on OutOfMemory? I suspect that
it is more a case of a vacuous requirement, not actually met in
practice.)
--
James Kanze
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