leo-claude-mktplace/plugins/code-sentinel/skills/refactoring-patterns.md

description

description
Code refactoring patterns and techniques for improving structure and maintainability

Refactoring Patterns Skill

Structure Patterns

Pattern	Description	When to Use
extract-method	Extract code block into named function	Long functions, repeated logic
extract-class	Move related methods to new class	Class doing too much
inline	Inline trivial function/variable	Over-abstracted code
rename	Rename with all references updated	Unclear naming
move	Move function/class to different module	Misplaced code

extract-method Example

# BEFORE
def process_order(order):
    # Validate (extract this)
    if not order.items:
        raise ValueError("Empty order")
    if order.total < 0:
        raise ValueError("Invalid total")
    # Process
    for item in order.items:
        inventory.reserve(item)
    return create_invoice(order)

# AFTER
def validate_order(order):
    if not order.items:
        raise ValueError("Empty order")
    if order.total < 0:
        raise ValueError("Invalid total")

def process_order(order):
    validate_order(order)
    for item in order.items:
        inventory.reserve(item)
    return create_invoice(order)

Simplification Patterns

Pattern	Description	When to Use
simplify-conditional	Flatten nested if/else	Deep nesting (>3 levels)
remove-dead-code	Delete unreachable code	After refactoring
consolidate-duplicate	Merge duplicate code blocks	DRY violations
decompose-conditional	Break complex conditions into named parts	Long boolean expressions

simplify-conditional Example

# BEFORE
if user:
    if user.active:
        if user.has_permission:
            do_action()

# AFTER (guard clauses)
if not user:
    return
if not user.active:
    return
if not user.has_permission:
    return
do_action()

Modernization Patterns

Pattern	Description	When to Use
use-comprehension	Convert loops to list/dict comprehensions	Simple transformations
use-pathlib	Replace os.path with pathlib	File path operations
use-fstring	Convert .format() to f-strings	String formatting
use-typing	Add type hints	Public APIs, complex functions
use-dataclass	Convert class to dataclass	Data-holding classes

use-dataclass Example

# BEFORE
class User:
    def __init__(self, name, email, age):
        self.name = name
        self.email = email
        self.age = age

# AFTER
@dataclass
class User:
    name: str
    email: str
    age: int

Code Smell Detection

Smell	Indicators	Suggested Pattern
Long Method	>20 lines, multiple responsibilities	extract-method
Large Class	>10 methods, low cohesion	extract-class
Primitive Obsession	Many related primitives	use-dataclass
Nested Conditionals	>3 nesting levels	simplify-conditional
Duplicate Code	Copy-pasted blocks	consolidate-duplicate
Dead Code	Unreachable branches	remove-dead-code

Metrics

After refactoring, measure improvement:

Metric	Good Target	Tool
Cyclomatic Complexity	<10 per function	radon, lizard
Function Length	<25 lines	manual count
Class Cohesion	LCOM <0.5	pylint
Duplication	<3%	jscpd, radon