How to properly use the try catch in perl that error.pm provides?

Question

I have found that there is the module Error that provides try and catch functionality like in java. But I am confused at how you can print the exception that returns.

I would like to understand how to do the following

try {     // do something that will fail!  } catch (Error e) {     // Print out the exception that occurred     System.out.println(e.getMessage()); } 

How do I get the print of the error with the stack trace?

Answer 1

You're probably better off using Try::Tiny which will help you avoid a number of pitfalls with older perls.

use Try::Tiny;  try {         die "foo"; } catch {         warn "caught error: $_"; }; 

Answer 2

Last I checked, Error was deprecated. But here's how you would do it without that module:

eval {     die "Oops!";     1; } or do {     my $e = $@;     print("Something went wrong: $e\n"); }; 

Basically, use eval instead of try, die instead of throw, and look for the exception in $@. The true value at the end of the eval block is part of an idiom to prevent $@ from unintentionally changing before it is used again in Perl versions older than 5.14, see P::C::P::ErrorHandling::RequireCheckingReturnValueOfEval for details. For example, this code suffers from this flaw.

# BAD, DO NOT USE WITH PERLS OLDER THAN 5.14 eval {     die "Oops!"; }; if (my $e = $@) {     print("Something went wrong: $e\n"); } # BAD, DO NOT USE WITH PERLS OLDER THAN 5.14 

---

But note that many Perl operations do not raise exceptions when they fail; they simply return an error code. This behavior can be altered via autodie for builtins and standard modules. If you're using autodie, then the standard way of doing try/catch is this (straight out of the autodie perldoc):

use feature qw(switch);  eval {    use autodie;     open(my $fh, '<', $some_file);     my @records = <$fh>;     # Do things with @records...     close($fh);  };  given ($@) {    when (undef)   { say "No error";                    }    when ('open')  { say "Error from open";             }    when (':io')   { say "Non-open, IO error.";         }    when (':all')  { say "All other autodie errors."    }    default        { say "Not an autodie error at all." } } 

For getting a stacktrace, look at Carp.