[boost] Re: Re: improved assertions?

From: Hendrik Schober (boost_at_[hidden])
Date: 2002-06-24 10:28:01

"Ted Byers" <r.ted.byers_at_[hidden]> wrote:
> > "Ted Byers" <r.ted.byers_at_[hidden]> wrote:
> > > [...]
> > > However, my base exception also allows for the user (the programmers'
> using
> > > code) to set a custom message for each place where an exception can be
> > > thrown.  so you could have something like:
> > >
> > > void f(void) {
> > >   ERROR_STACKTRACE_BEGIN
> > >   static std::string msg;
> > >   static const std::string msgA("Here");
> > >   msg = msgA;
> > >   bool rcA = Herefunction();
> > > ...
> > >   static const std::string msgB("There");
> > >   bool rcB = ThereFunction();
> > > ...
> > >   ERROR_STACKTRACE_END
> > > };
>
> [...]
>
> Second, the strings I am using are static constant strings, except for the
> one used directly by my macros, so if I understand things correctly, they'll
> be already constructed in the data segment of the program once the program
> is running [...]

  I doubt that many compilers will compile-time-initialize 
  UDTs. 

> [...]  If this is correct, to have this usage not throw, all I
> have to focus on the default and copy constructors, and assignment operator.

  Why don't you simply avoid the copying? 

    static std::string* msg;
    static const std::string msgA("Here");
    msg = &msgA;
    bool rcA = Herefunction();
    ...
    static const std::string msgB("There");
    msg = &msgB;
    bool rcB = ThereFunction();

  Once you do that, you might as well use 'char*' anyway. 
  I doubt any compiler would _not_ init that at compile 
  time. :)

> But using more try/catch blocks does not get rid of the string problem
> because most of the data members in my traceable exception classes are
> std::string.  Thus, I have to alter my use of them, or replace them, so that
> default and copy construction, and assignment, do not throw anyway,
> regardless of whether I use multiple try/catch blocks or my message strings.

  Maybe COW should do that. 

> [...]
> >   I don't know much about the details of SEH, but I think these
> >   exceptions are synchronous. But I really don't knwo that.
> >
> I was wondering aloud here about "how did they do that?"  Presumably the OS
> has to use a signal handler to get the hardware exceptions, in order to be
> able to throw a structured exception.  But if you can't do much but set an
> atomic flag, how did they do it?  And if they can do it, why can't we?

  As I said, I don't know much about how they did that. 
  (But I don't see why they need an implementation based 
  on signals.) 

> Cheers,
> 
> Ted

  Schobi