On Thu, Sep 30, 2010 at 8:34 PM, C.DeRykus <dery...@gmail.com> wrote:
> On Sep 30, 7:37 pm, jon.herman...@gmail.com (Jon Hermansen) wrote:
> > Hey all,
> > I have this block of code:
> >
> > sub is_valid_xml {
> >
> > > my ($content) = @_;
> >
> > > eval {
> > > my $xs = XML::Simple->new();
> > > my $ref = $xs->parse_string($content);
> > > };
> >
> > > return 1 unless ($@);
> > > }
> >
>
> block eval will already trap fatal errors and set
> $@ and return the undefined value or an empty
> list depending on context. If there's no error,
> then the value of the last expression evaluated
> is returned. See: perldoc -f eval
>
> So, one possibility:
>
> sub is_valid_xml {
>
> my ($content) = @_;
>
> my $ret = eval {
> my $xs = XML::Simple->new();
> my $ref = $xs->parse_string($content);
> 1; # ensure true value if no fatalities
> };
> return $ret;
> }
>
> then just call the sub in scalar context and
> check for an error:
>
> is_valid_xml( "blah") or die "invalid: $@";
>
> > and when I pass in 'blahblahblah' as an argument, I get:
> >
> > syntax error at line 1, column 0, byte 0 at /usr/lib/perl5/XML/Parser.pm
> >
> > > line 187
> >
> > I would like to trap this syntax error, but don't know how. I've tried
> each
> > of these statements individually:
> >
> > local $SIG{'__DIE__'};
> >
> > > local $SIG{'__WARN__'};
> > > no warnings 'all';
>
> check 'perldoc -f eval' for additional info if you're trying to
> trap warnings too.
>
> --
> Charles DeRykus <http://learn.perl.org/>
>
>
Charles,
Thanks for the help. I was able to find a few workarounds with your
examples. I found something interesting in my testing-- at the end of my
sub, if instead of:
return 1 unless ($@);
>
I use:
if (not $@) {return 1;}
>
OR
return 1 if (not $@);
>
the syntax error does not get printed out. I assumed that these statements
were logically equal, so, what gives?
