beginners:
After RTFM, STFW, etc., I realized that print() was issuing a warning
and continuing.
I came up with two solutions:
1. perldoc -f print() states "Returns true if successful". So:
print $s @_ or die $!;
The downside is that the warning still gets printed:
print() on unopened filehandle NOSUCH at trap-print-errors2.pl line 12.
And $! isn't very meaningful:
trapped error Bad file descriptor at trap-print-errors2.pl line 12.
2. The warnings pragmatic module has an option for turning warnings
into errors:
use warnings FATAL => 'all';
print $s @_;
This eliminates the warning message and gives me a meaningful $@:
trapped error print() on unopened filehandle NOSUCH at
trap-print-errors2.pl line 24.
Much better! :-)
HTH,
David
2011-01-16 15:47:28 dpchrist@p43400e ~/sandbox
$ cat trap-print-errors2.pl
#!/usr/bin/perl
use strict;
use warnings;
$| = 1;
sub myprint($@)
{
my $s = shift;
eval {
### circumvent Can't use string ("*STDOUT") as a symbol ref...
no strict 'refs';
print $s @_ or die $!;
};
print "trapped error $@" if $@;
}
sub myprint2($@)
{
my $s = shift;
eval {
### circumvent Can't use string ("*STDOUT") as a symbol ref...
no strict 'refs';
use warnings FATAL => 'all';
print $s @_;
};
print "trapped error $@" if $@;
}
myprint '*STDOUT', "hello, world!\n";
myprint2 '*STDOUT', "hello, world!\n";
myprint '*NOSUCH', "goodbye, cruel world!";
myprint2 '*NOSUCH', "goodbye, cruel world!";
print "all done\n";
2011-01-16 15:48:02 dpchrist@p43400e ~/sandbox
$ perl -c trap-print-errors2.pl
trap-print-errors2.pl syntax OK
2011-01-16 15:48:09 dpchrist@p43400e ~/sandbox
$ perl trap-print-errors2.pl
hello, world!
hello, world!
print() on unopened filehandle NOSUCH at trap-print-errors2.pl line 12.
trapped error Bad file descriptor at trap-print-errors2.pl line 12.
trapped error print() on unopened filehandle NOSUCH at
trap-print-errors2.pl line 24.
all done
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