Path: news.cs.au.dk!not-for-mail
From: "Sascha Kimmel" <kimmel@tricos.com>
Newsgroups: comp.lang.beta
Subject: RE: exceptions: (atle // confused (# again #) atle)
Date: 19 Jun 2000 17:38:48 -0000
Organization: University of Aarhus, Department of Computer Science (DAIMI)
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> -----Original Message-----
> From: Atle [mailto:trollet@skynet.be]
> Sent: Monday, June 19, 2000 7:02 PM
> To: usergroup@mjolner.dk
> Subject: Re: exceptions: (atle // confused (# again #) atle)
>
>
> Sascha Kimmel wrote:
> >
> >
> > >       returnValue := openFile('SomeFile.bet')
> > >       IF returnValue <> OK
> > >       THEN produceError(returnValue);
> > >       ELSE
> > >       { do the normal processing.
> > >       returnValue will be a legal file handle }
> > >       ENDIF
> >
> > Hey, I like this code :)
> But how well does it correspond to Beta exception handling?

Not much...


> >
> > >       try {
> > >               strm = bufferedstreamandsomestuffandtotallyunreadable
> > (filename, OPENFLAGS);
> > >       }
> > >
> > >       catch(...) {
> > >               cout << "The program has been somewhere and crashed" <<
> > >               " difficult to say if I should recover or what?";
> > >       }
> >
> > Plase put away this JAVA stuff... ;)
> This is an example of 'dynamic exceptions' if I have understood
> things right - but have I?

Don't ask me much about JAVA, I've just started to look at JAVA, although I
think that JAVA is not a good language for programs, only for applets!


> > > So, i know i will like the Beta way. But what way is it?
> >
> >
> > But I doubt that this is more intuitive than the "old" way which many
> > languages like Perl and PHP also use.
> > But object-oriented is "modern".
> Problem is, I don't see the difference. It looks to me as if the
> errors are handled 'as much as possible' inside the object, and

Yes, inside the object, that is the difference!


> that whatever isn't handled there is propagated back out to the
> calling object. But there must be more to it than that?

No, if you don't "catch" an exception, you BETA program will be stopped,
there's no such propagation AFAIK.


> > The problem in BETA is:
> >
> > [...]
> > myfile:@file(# (..now handle the different errors...) #);
> > [...]
> >
> > .code...
> > ..more code...
> > .. a hundred lines of code...
> >
> > [...]
> > myfile.openRead;
> > [...]
> But errors are handled here, too. Like NoSuchFileError - I need

They are HANDLED there, yes, but not DECLARED!
I just wanted to show that it's sometimes very hard to see what MIGHT happen
(NoSuchFileError,AccessError etc.) if you have defined these files hundreds
of lines above!


> to look over that again from the cat.bet example.
> Jørgen, could you please add more context around your code
> snippet, please?
> >
> > Example 1. fopen() example
> >
> >    $fp = fopen("/home/rasmus/file.txt", "r");
> >    $fp = fopen("http://www.php.net/", "r");
> >    $fp = fopen("ftp://user:password@example.com/", "w");
> This, however horrifies me.
>
> OK in an rc file, but not in a program!

RC file????

You simply do:
------------X<-----------------------------------------------
$fd = fopen ("/tmp/inputfile.txt", "r");
while (!feof($fd)) {
    $buffer = fgets($fd, 4096);
    echo $buffer;
}
fclose ($fd);
------------X<-----------------------------------------------

This is NOT a definition, $fp ($fd) simply is the file HANDLE!
In PHP and Perl you do not need to define any variables, variables have no
specific type and are handled context-sensitive!

Regards,
Sascha Kimmel