Re: [Boost-users] serialization gives memory leaks due to throwing constructors

From: David Abrahams (dave_at_[hidden])
Date: 2007-03-05 08:37:42

gast128 <gast128_at_[hidden]> writes:

> Hello David,
>
> my point is that exceptions are fatal when not dealt with. This can
> be a good thing in case of fatal exceptions (e.g. memory
> exhaustion),

Whether or not memory exhaustion should be fatal to a program is open
to debate, but if you do need to shut the program down completely and
quickly, exceptions are usually not the right mechanism to do it
(http://groups.google.com/group/comp.lang.c++.moderated/browse_frm/thread/80083ac31a1188da/200743f260401436?#200743f260401436)

> but bad when the exceptions are not that severe (e.g. string length
> on a NULL string).

If that's a programming bug, it should almost certainly *not* throw an
exception.

> Another item is that I think that one of the rationales is that it is cleaner 
> to write code like:
>
> void Foo()
> {
>    try
>    {
>       //write logic
>    }
>    catch ()
>    {
>       //write exception case(s)
>    }
> }

Rationales, for what?  Cleaner than what?

> This throwing ctor stuff can be annoying if one considers the follwing case:
>
> void GetAllEmployees()
> {
>    std::vector<Employee> v;
>
>    Employee e = Load(...)
>    v.push_back(e);
>    
>    //etc.
> }
>
> consider that one of the employees can 'become' corrupt. 

It's almost impossible to write reasonable programs when you have to
"consider that one of the xxx objects can 'become' corrupt."  
http://groups.google.com/group/comp.lang.c++.moderated/msg/659b9db50f587dab

> But still the rest of 
> the employees should be dealt with. With exception handling it becomes:
>
> void GetAllEmployees()
> {
>    std::vector<Employee> v;
>
>    try
>    {
>      Employee e = Load(...)
>      v.push_back(e);
>    }
>    catch ()
>    {
>    }
>
>    //etc.
> }
>
> No more nice seperation between logic and exception.

I don't know why anyone would do that.  Which employee has 'become'
corrupt here, and how does the above code supposedly help?  It seems
to just eat exceptions and mask errors, nothing more.

-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com