EXP30-PL. Do not use deprecated or obsolete functions

Do not use deprecated or obsolescent functions when more secure equivalent functions are available.

Here is a list of deprecated functions, along with their recommended alternatives, if available:

Deprecated	Preferred
`UNIVERSAL::can()`	object `can()` method
`UNIVERSAL::isa()`	object `isa()` method
`die()`	`Carp::croak()`
`warn()`	`Carp::carp()`
`-t`	`IO::Interactive`
`format()`	`Template`, `Perl6::Form`

Noncompliant Code Example (`die()`)

This noncompliant code example tries to open a file, and invokes the obsolete die() method if it fails.

my $file;
open(FILE, "<", $file) or die "error opening $file: stopped";
# work with FILE

The die() method is considered deprecated, as it prints the file name and line number in which it was invoked. This might be sensitive information.

Compliant Solution (`croak()`)

This compliant colution uses the croak() function instead of die().

use Carp;

my $file;
open(FILE, "<", $file) or croak "error opening $file: stopped";
# work with FILE

Unlike, die(), croak() provides the filename and line number of the function that invoked the function that invoked croak(). This is more useful for application code that invokes library code; in this case croak() and carp() also will reveal the file name and line number of the application code rather than the library code.

Risk Assessment

Failure to handle error codes or other values returned by functions can lead to incorrect program flow and violations of data integrity.

Recommendation	Severity	Likelihood	Remediation Cost	Priority	Level
EXP30-PL	info	probable	low	P12	L1

Automated Detection

Tool	Diagnostic
Perl::Critic	BuiltinFunctions::ProhibitUniversalCan
	BuiltinFunctions::ProhibitUniversalIsa
	ErrorHandling::RequireCarping
	InputOutput::ProhibitInteractiveTest
	Miscellanea::ProhibitFormats