aiyshwarya

• Nov 19th, 2007

 

 "eval" and "if ($@)" is the equivalent of a try/catch in the C
programming world. My question is how to basically throw an error in
one perl script that can be caught by another

Consider the following example:

eval {

die("REASON"); # the script dies for some reason

};

if ($@) # $@ contains the exception that was thrown
{
print $@;
}


thanks
Aiyshwarya

acraul7

 Profile Answers by acraul7 

• Mar 5th, 2008

 

eval is also used for evaluating expressions.
For eg:
$a = 1;
$b = 3;
$c = '$a*$b';
print(eval "$c"); // This prints 3

sapam

 Profile Answers by sapam Questions by sapam

• Mar 31st, 2008

 

The eval function provides a very simple way of checking certain events without affecting the overall execution of your script. In essence, the eval function just initiates a new instance of the Perl interpreter in order to evaluate a particular string or block. It’s used in all sorts of places within Perl—including in the debugger where it allows you to execute those arbitrary statements—but it can also be employed as a debugging tool.

Because eval evaluates a Perl statement or block within its own interpreter, we can use it in situations that might otherwise cause the Perl interpreter to fail. This process works because an embedded eval block reports any errors raised by a call to die through the $@ variable. In fact, any exit is reported through eval to the $@ special variable. We can demonstrate this with a simple eval block used to test the existence of a particular module:

eval
{
require Net::FTP;
}
print "Error: Module failed to load ($@)" if $@;

This outputs the following:

$ perl eval.pl
Failed to load Net::FTP: Can't locate Net/LICK.pm in @INC (@INC contains:
/usr/local/lib/perl5/5.6.0/i686-linux /usr/local/lib/perl5/5.6.0
/usr/local/lib/perl5/site_perl/5.6.0/i686-linux
/usr/local/lib/perl5/site_perl/5.6.0 /usr/local/lib/perl5/site_perl .) at
eval.pl line 1.