RE: Can I set '$!' ?

From: Daniel Staal (DStaal_at_usa.net)
Date: 12/29/03 

Date: Mon, 29 Dec 2003 14:17:33 -0500
To: Perl Newbies <beginners@perl.org>

--As off Monday, December 29, 2003 12:54 PM -0600, Dan Muey is
alleged to have said:

>> I want to be able to return a true or false value from a
>> function in a module and populate the $! variable with the
>> specific errors. Is this possible? Is there documentation on
>> how to do this? I can find docs on how to use $! but not how
>> to set it. Thanks for any help -Ken
>
> Did anyone ever reply to this post?
> I couldn't find it in the archives and I thinnk it's a pretty good
> question.

There were several responses, I can forward them to you if you really
want them. Basically it boiled down to: "Read 'perldoc perlvar' for
how and possible values.", and "Are you sure you want to do that?".

> For instance would it be 'safe' and 'proper', and 'ok', etc... to
> do somethign like:
>
> sub whatever {
> my $foo = shift;
> undef $!;
> if($foo eq 'bar') { return 1; }
> else { $! = "Foo must equal bar";return 0; }
> }

"Foo must equal bar" is not a valid value for $!, most likely. :-)
For what you are doing here I would really prefer you either 'die' or
'warn', depending on what severity you think the problem is. (You
could of course 'croak' or 'carp' instead, as applicable.)

Daniel T. Staal

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