Re: efficient exception handling

terminator wrote:

: On Oct 15, 1:17 pm, Erik Wikstr=F6m <Erik-wikst...@telia.com> wrote:
::
:: Consider the following, an exception is thrown in a constructor.
:: In the catch-block you use continue to resume the execution which
:: means that
:: your code will continue to run and try to perform operations on a
:: not
:: fully constructed object. Not a good idea. The reason the
:: exception was thrown was that correct execution was no longer
:: possible, the only
:: correct way of handling this is to go back a little and then deal
:: with
:: the situation (by aborting, trying again, trying something
:: different, etc.).
::
:
: I see : Since throw is usually used as a conditional jump, the next
: instruction is executed with the assumption that oposite of the
: condition is true where a continue can not fix the affected data.
: The solution is easy ,one must avoid a 'continue'd catch block for
: old exception classes thrown by hopeless outdated algorithms that
: do not consider a second chance .
:
: A 'throw' statement can reflect the source of error instead of just
: nagging:
:
: class foo{
: public:
: foo()throw(foo*){
: if(some_problem)
: throw this;
: };
: };

If the constructor throws, there will be no foo object. The this
pointer has nothing to point to!

It looks as if the stack unwinding is performed at 'throw'
site .but IMHO if the stack unwinding is left to the 'catch' site the
program will be more flexible;because it gives us the option to handle
the trouble and resume the program from the statement after the
throw ,rather than stopping what was performing before the
throw.Therefore a default exception handler also need be implicitly
defined ,so that it can catch all exeptions and do nothing but unwind
the stack and terminate.

:
: bool fix(foo *);
:
: try{
: foo obj;
: }catch(foo * what){
: if (fix(what))
: continue;//(*what) is valid now.
: throw;//could not solve it:reporting daddy
: }

If you know how to fix the problem for foo, why not just pass it the
fix function in its constructor, and let if fix itself up?