Perl Lint

Perl Linting and Formatting

Run Perl::Critic analysis and perltidy formatting with automatic tool detection.

Workflow

1. Check if perlcritic/perltidy are installed
2. Run analysis on specified files
3. Report findings with severity levels
4. Suggest fixes or format code

Tool Detection

First, verify tools are available:

# Check perlcritic
command -v perlcritic >/dev/null && echo "perlcritic available" || echo "Install: cpanm Perl::Critic"

# Check perltidy
command -v perltidy >/dev/null && echo "perltidy available" || echo "Install: cpanm Perl::Tidy"

Perl::Critic Analysis

Running perlcritic

# Default analysis (severity 5 - gentle)
perlcritic script.pl

# All severities (1 = strictest)
perlcritic --severity 1 script.pl

# Specific severity level
perlcritic --severity 3 script.pl

# With verbose explanations
perlcritic --verbose 11 script.pl

# Single policy
perlcritic --single-policy RequireUseStrict script.pl

# Exclude policies
perlcritic --exclude RequireUseWarnings script.pl

Severity Levels

Common Policies

Configuration File

Create .perlcriticrc in project root:

# .perlcriticrc
severity = 3
verbose = 8
theme = core

# Exclude specific policies
[-Documentation::RequirePodSections]
[-InputOutput::RequireBriefOpen]

# Configure specific policy
[CodeLayout::RequireTidyCode]
perltidyrc = .perltidyrc

[Variables::ProhibitPackageVars]
packages = Data::Dumper File::Find

[TestingAndDebugging::ProhibitNoStrict]
allow = refs

Verbose Formats

Perltidy Formatting

Basic Usage

# Format file (creates .bak backup)
perltidy script.pl

# Format to stdout (no backup)
perltidy -st script.pl

# In-place edit (no backup)
perltidy -b -nst script.pl

# Check if tidy (exit code)
perltidy -st script.pl | diff -q - script.pl

Common Options

# Basic formatting
perltidy -i=4 -ci=4 -l=100 script.pl

# Full command with common options
perltidy \
    --indent-columns=4 \
    --continuation-indentation=4 \
    --maximum-line-length=100 \
    --vertical-tightness=2 \
    --paren-tightness=1 \
    --brace-tightness=1 \
    script.pl

Configuration File

Create .perltidyrc in project root:

# .perltidyrc

# Indentation
--indent-columns=4
--continuation-indentation=4

# Line length
--maximum-line-length=100

# Blank lines
--blank-lines-before-subs=1
--blank-lines-after-block-opening=0

# Spaces
--paren-tightness=1
--brace-tightness=1
--square-bracket-tightness=1

# Vertical alignment
--no-outdent-long-quotes
--no-outdent-long-comments

# Output
--backup-and-modify-in-place
--backup-file-extension=/

Combined Workflow

Lint and Fix

#!/bin/bash
# lint-perl.sh

FILE="$1"

if [[ ! -f "$FILE" ]]; then
    echo "Usage: lint-perl.sh <file.pl>"
    exit 1
fi

echo "=== Syntax Check ==="
perl -c "$FILE" || exit 1

echo ""
echo "=== Perl::Critic ==="
if command -v perlcritic >/dev/null; then
    perlcritic --severity 4 "$FILE"
else
    echo "perlcritic not installed. Run: cpanm Perl::Critic"
fi

echo ""
echo "=== Formatting Check ==="
if command -v perltidy >/dev/null; then
    if ! perltidy -st "$FILE" | diff -q - "$FILE" >/dev/null 2>&1; then
        echo "File needs formatting. Run: perltidy $FILE"
    else
        echo "File is properly formatted."
    fi
else
    echo "perltidy not installed. Run: cpanm Perl::Tidy"
fi

Interpreting Results

Severity 5 (Critical)

Must fix immediately:

Bareword file handle opened at line 10, column 1.
Two-argument "open" used at line 15, column 5.

Fix:

# Wrong
open FILE, $filename;

# Correct
open my $fh, '<', $filename;

Severity 4 (Important)

Should fix:

Code before strictures are enabled at line 1.

Fix:

# Add at top
use strict;
use warnings;

Severity 3 (Recommended)

Consider fixing:

Regular expression without "/x" flag at line 25.

Installation

If tools are missing:

# Install both tools
cpanm Perl::Critic Perl::Tidy

# Verify installation
perlcritic --version
perltidy --version

Quick Commands

Lint specific file:

perlcritic --severity 4 --verbose 8 path/to/file.pl

Lint all Perl files in directory:

find . -name '*.pl' -o -name '*.pm' | xargs perlcritic --severity 4

Format all files:

find . -name '*.pl' -o -name '*.pm' | xargs perltidy -b