| name | syntax-keyword-assert-perl |
| description | Use Syntax::Keyword::Assert for zero-cost assertions in Perl |
| version | 1.0.0 |
| author | kfly8 |
| tags | ["perl","cpan","assert","debugging","syntax-extension"] |
Syntax::Keyword::Assert - Zero-Cost Assertions
Syntax::Keyword::Assert provides an assert keyword for Perl with zero runtime cost when disabled.
Core Function
assert EXPR
use Syntax::Keyword::Assert;
assert $x > 0;
assert $obj isa "MyClass";
assert defined $value;
assert "apple" eq "banana";
Key Features
Zero Runtime Cost
When assertions are disabled, they are completely removed at compile time:
assert expensive_check();
Environment Control
$ENV{PERL_ASSERT_ENABLED} = 0;
use Syntax::Keyword::Assert;
use Syntax::Keyword::Assert;
Practical Examples
Input Validation
sub divide {
my ($a, $b) = @_;
assert defined $a && defined $b;
assert $b != 0;
return $a / $b;
}
Object Type Checking
sub process_user {
my $user = shift;
assert $user isa "User";
assert $user->can("get_name");
return $user->get_name();
}
Development Debugging
sub complex_algorithm {
my @data = @_;
assert @data > 0;
my $result = process_data(@data);
assert defined $result;
assert ref($result) eq 'HASH';
return $result;
}
Contract Programming
sub fibonacci {
my $n = shift;
assert $n >= 0;
my $result = $n <= 1 ? $n : fibonacci($n-1) + fibonacci($n-2);
assert $result >= 0;
return $result;
}
Production Deployment
Disable in Production
BEGIN {
$ENV{PERL_ASSERT_ENABLED} = 0 if $ENV{PRODUCTION};
}
use Syntax::Keyword::Assert;
Conditional Assertions
use Syntax::Keyword::Assert;
sub critical_function {
my $data = shift;
assert validate_complex_invariant($data);
return process($data);
}
Best Practices
- Use for debugging: Add assertions during development, disable in production
- Check invariants: Verify assumptions about data state and object types
- Validate inputs: Assert preconditions for function parameters
- Document assumptions: Assertions serve as executable documentation
- Zero-cost safety: Enable aggressive checking without production performance penalty