软件工程中的 7 种代码重构技术

在软件开发的过程中，代码可能会变得越来越复杂和难以维护。而代码重构就是一种通过重新组织代码结构，以达到更好的可读性、可维护性和可扩展性的软件开发技术。在本文中，我们将介绍软件工程中常见的 7 种代码重构技术。

1. Rename

重命名是一种简单但非常有用的编码技巧。它可以帮助改善代码的可读性和可理解性。通常，我们使用一个更准确的名称来替代一个变量、函数或类的旧名称。这个新名称应该更符合其功能或实现。

# Rename before:
def a(x):
    return x ** 2

# Rename after:
def square(x):
    return x ** 2

2. Extract Function

Extract Function 是一种重构方法，将代码片段转换为一个独立的函数。这样做可以提高代码的可读性和可维护性，减少重复代码，并使代码更易于测试和扩展。

# Extract Function before:
def calculate_salary(employee):
    total_working_hours = employee.get_total_working_hours()
    hourly_rate = employee.hourly_rate
    salary = total_working_hours * hourly_rate
    if employee.is_manager:
        salary += 1000
    return salary

# Extract Function after:
def calculate_salary(employee):
    total_working_hours = employee.get_total_working_hours()
    hourly_rate = employee.hourly_rate
    salary = calculate_base_salary(total_working_hours, hourly_rate)
    if employee.is_manager:
        salary += calculate_manager_bonus()
    return salary

def calculate_base_salary(total_working_hours, hourly_rate):
    return total_working_hours * hourly_rate

def calculate_manager_bonus():
    return 1000

3. Inline Function

Inline Function 是 Extract Function 的逆过程。它将函数调用替换为函数本身的所有内容。这种重构方法可以帮助消除不必要的复杂性和提高代码的可读性。

# Inline Function before:
def calculate_salary(employee):
    return get_base_salary(employee) + get_manager_bonus(employee)

def get_base_salary(employee):
    total_working_hours = employee.get_total_working_hours()
    hourly_rate = employee.hourly_rate
    return total_working_hours * hourly_rate

def get_manager_bonus(employee):
    if employee.is_manager:
        return 1000
    else:
        return 0

# Inline Function after:
def calculate_salary(employee):
    total_working_hours = employee.get_total_working_hours()
    hourly_rate = employee.hourly_rate
    salary = total_working_hours * hourly_rate
    if employee.is_manager:
        salary += 1000
    return salary

4. Extract Class

Extract Class 是将一部分相关的属性和方法从一个类中提取出来，创建一个新的类的重构方法。这可以帮助保持类的简洁性和清晰性，并降低代码的复杂性。

# Extract Class before:
class Employee:
    def __init__(self, name, phone, email, hourly_rate, total_working_hours, is_manager):
        self.name = name
        self.phone = phone
        self.email = email
        self.hourly_rate = hourly_rate
        self.total_working_hours = total_working_hours
        self.is_manager = is_manager

    def calculate_salary(self):
        salary = self.total_working_hours * self.hourly_rate
        if self.is_manager:
            salary += 1000
        return salary

# Extract Class after:
class Employee:
    def __init__(self, name, phone, email):
        self.name = name
        self.phone = phone
        self.email = email
        self.job_title = None
        self.pay_type = None

class HourlyEmployee(Employee):
    def __init__(self, hourly_rate, total_working_hours):
        super().__init__()
        self.hourly_rate = hourly_rate
        self.total_working_hours = total_working_hours

    def calculate_salary(self):
        salary = self.total_working_hours * self.hourly_rate
        return salary

class SalariedEmployee(Employee):
    def __init__(self, monthly_salary):
        super().__init__()
        self.monthly_salary = monthly_salary

    def calculate_salary(self):
        return self.monthly_salary

5. Move Method

Move Method 是将方法从一个类中移到另一个类的重构方法。这样做可以提高类的聚合性和耦合性，并使代码更容易扩展和维护。

# Move Method before:
class Employee:
    def __init__(self, name, phone, email, hourly_rate, total_working_hours, is_manager):
        self.name = name
        self.phone = phone
        self.email = email
        self.hourly_rate = hourly_rate
        self.total_working_hours = total_working_hours
        self.is_manager = is_manager

    def calculate_salary(self):
        salary = self.total_working_hours * self.hourly_rate
        if self.is_manager:
            salary += 1000
        return salary

    def print_employee_info(self):
        print('Name: {}'.format(self.name))
        print('Phone: {}'.format(self.phone))
        print('Email: {}'.format(self.email))


class Manager(Employee):
    def __init__(self, name, phone, email, hourly_rate, total_working_hours):
        super().__init__(name, phone, email, hourly_rate, total_working_hours, is_manager=True)


# Move Method after:
class Employee:
    def __init__(self, name, phone, email):
        self.name = name
        self.phone = phone
        self.email = email

    def print_employee_info(self):
        print('Name: {}'.format(self.name))
        print('Phone: {}'.format(self.phone))
        print('Email: {}'.format(self.email))

class Payroll:
    def __init__(self, hourly_rate, total_working_hours):
        self.hourly_rate = hourly_rate
        self.total_working_hours = total_working_hours

    def calculate_salary(self):
        salary = self.total_working_hours * self.hourly_rate
        return salary

class Employee:
    def __init__(self, name, phone, email):
        self.name = name
        self.phone = phone
        self.email = email
        self.payroll = None

    def set_payroll(self, payroll):
        self.payroll = payroll

    def calculate_salary(self):
        return self.payroll.calculate_salary()

class Manager(Employee):
    def __init__(self, name, phone, email, hourly_rate, total_working_hours):
        super().__init__(name, phone, email)
        self.set_payroll(HourlyPayroll(hourly_rate, total_working_hours))

6. Replace Conditional with Polymorphism

Replace Conditional with Polymorphism 是一种重构技术，将一系列的条件分支语句替换为多态的形式。这可以使代码更加清晰和易于维护。

# Replace Conditional with Polymorphism before:
class Employee:
    def __init__(self, name, phone, email, hourly_rate, total_working_hours, is_manager):
        self.name = name
        self.phone = phone
        self.email = email
        self.hourly_rate = hourly_rate
        self.total_working_hours = total_working_hours
        self.is_manager = is_manager

    def calculate_payroll(self):
        if self.is_manager:
            salary = self.total_working_hours * self.hourly_rate + 1000
        else:
            salary = self.total_working_hours * self.hourly_rate
        return salary

class Manager(Employee):
    def __init__(self, name, phone, email, hourly_rate, total_working_hours):
        super().__init__(name, phone, email, hourly_rate, total_working_hours, is_manager=True)

# Replace Conditional with Polymorphism after:
class Payroll:
    def calculate_payroll(self, employee):
        pass

class HourlyPayroll(Payroll):
    def calculate_payroll(self, employee):
        return employee.total_working_hours * employee.hourly_rate

class ManagerPayroll(Payroll):
    def calculate_payroll(self, employee):
        return employee.total_working_hours * employee.hourly_rate + 1000

class Employee:
    def __init__(self, name, phone, email, payroll):
        self.name = name
        self.phone = phone
        self.email = email
        self.payroll = payroll

    def calculate_payroll(self):
        return self.payroll.calculate_payroll(self)

class Manager(Employee):
    def __init__(self, name, phone, email, hourly_rate, total_working_hours):
        payroll = ManagerPayroll()
        super().__init__(name, phone, email, payroll)

7. Remove Duplication

Remove Duplication 是一种简单而常见的重构技术，目的是消除代码中的重复部分。

# Remove Duplication before:
def area_square(x):
    return x ** 2

def volume_cube(x):
    return x ** 3

# Remove Duplication after:
def power(x, n):
    return x ** n

def area_square(x):
    return power(x, 2)

def volume_cube(x):
    return power(x, 3)

以上就是 7 种常见的软件工程中的代码重构技术，程序员可以根据需要，在实际的代码开发中选择适合的重构方法，以提高代码的可读性、可维护性和可扩展性。