Path: utzoo!attcan!uunet!ginosko!usc!ucsd!ucrmath!proton!meson!nusbaum
From: nusbaum@meson.uucp (R. James Nusbaum)
Newsgroups: comp.lang.c++
Subject: Re: Handling trouble in C++
Keywords: exception error
Message-ID: <463@proton.UUCP>
Date: 24 Aug 89 21:20:15 GMT
References: <13262@well.UUCP>
Sender: news@proton.UUCP
Reply-To: nusbaum@meson.UUCP (R. James Nusbaum)
Distribution: comp
Organization: Loma Linda U. Rad. Research Lab, Loma Linda
Lines: 28

In article <13262@well.UUCP> nagle@well.UUCP (John Nagle) writes:
>
>     In C++, unlike C, a considerable fraction of the execution can
>take place implicitly, within constructors and destructors, rather
>than in explicitly called functions.  But there is no way for a
>constructor or a destructor to signal an error condition to the
>invoker.  Declarations aren't allowed to fail.  But constructors
>often do such things as open files, windows, devices, or databases.
>Such operations can fail.  What then?
>
>
>					John Nagle

One solution I used was to define a signal (SIGUSR1) as the 'constructor
failed' signal.  Then my constructors would raise this signal whenever
they failed while initializing an object on the stack.  The user could
then define a signal handler for this signal or just let the signal halt
the program.  Obviously this won't work on systems without signals and I
believe the method used by constructors to determine if the object was
on the stack was also not very portable.




Jim Nusbaum
Radiation Research Laboratory
Loma Linda University Medical Center
nusbaum%proton.uucp@ucrmath.ucr.edu