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vladionair
Asked:2020-11-17 01:13:56 +0000 UTC2020-11-17 01:13:56 +0000 UTC

在 python 类中使用装饰器

  • 772

我需要你的帮助）在第一个示例中，当在函数中使用装饰器时，我随后可以单独使用装饰函数（calc），但在第二个示例中，我不能：/如何做到这一点？？？！

示例 1：

def prog(calc):
    def print_res():
        calc()
        print('print result')
    return print_res
def calc():
    print('calculate')
x = prog(calc)
x()
print()
calc()

结论：

calculate
print result

calculate

示例 2：

class A:
    def __init__(self, l = 0):
        self.l = l
    def account(calc):
        def print_res(self, n, m):
            calc(self, n, m)
            print('result =', self.l)
        return print_res
    @account
    def calc(self, n, m):
        self.l = n + m
test = A()
test.calc(1, 1)

结论：

result = 2
python-3.x

3 个回答

  1. Best Answer

    你有一个不一致的电话。第一种情况，没有指定修饰，函数作为参数传递。在第二种情况下，它将适用于任何呼叫。另外，装饰函数写成静态的（没有自我），但这没有标记。因此，可能有几种解决方案。例如

    class A:
    def __init__(self, l = 0):
        self.l = l
    @staticmethod
    def account(calc):
        def print_res(self, n, m):
            self.calc(n, m)
            print('print result =', self.l)
        return print_res
    def calc(self, n, m):
        print('calculate')
        self.l = n + m
x = A.account(A.calc)
test = A()
x(test, 1,1)
test.calc(1, 1)

    这样的结论会是什么

    计算
    打印结果 = 2
    计算

    • 1 
  2. class A:
    def prog(calc):
        def print_res():
            calc()
            print('print result')
        return print_res
    def calc():
        print('calculate')
    x = prog(calc)
    x()
A.calc()
    • 0

  3. 嗯，总的来说，这就是它的用途...... :)

    class Accountant:
def __init__(self, a = [], b = [], c = [], n = 0, m = 0, sr = 0, sc = 0, tr = 0, tc = 0, value = 0):
    self.a = a
    self.b = b
    self.c = c
    self.n = n
    self.m = m
    self.sr = sr
    self.sc = sc
    self.tr = tr
    self.tc = tc
    self.value = value
@staticmethod
def account(calc):
    def print_res(self, n, m):
        self.calc(n, m)
        print()
        print('Введены данные: число строк:', self.n,',', 'число колонн:', self.m, '.')
        print()
        for i in range(self.n):
            for j in range(self.m):
                print(self.a[i][j], end=' ')
            print()
        print()
        print('Проверьте правильность заполнения таблицы!')
        print()
        if self.tr == self.tc:
            print('Сумма строк:', self.tr, '.', 'Суммы строк:', self.b, '.')
            print()
            print('Сумма столбцов:', self.tc, '.', 'Суммы столбцов:', self.c, '.')
            print()
            print('Баланс сведен.')
            print()
        else:
            print('В расчетах ошибка!')
    return print_res
def calc(self, n, m):
    self.n = n
    self.m = m
    def creat_array():
        import random
        for i in range(n):
            self.a.append([])
            for j in range(m):
                self.value = random.randint(-10, 10)
                self.a[i].append(self.value)
    def sum_row():
        for i in range(n):
            for j in range(m):
                self.sr += self.a[i][j]
                self.tr += self.a[i][j]
            self.b.append(self.sr)
            self.sr = 0
    def sum_col():
        for i in range(m):
            for j in range(n):
                self.sc += self.a[j][i]
                self.tc += self.a[j][i]
            self.c.append(self.sc)
            self.sc = 0
    creat_array()
    sum_row()
    sum_col()
check = Accountant()
x = Accountant.account(Accountant.calc)

#x(check, int(input('Введите значение n:')), int(input('Введите значение m:')))
#check.calc(int(input('Введите значение n:')), int(input('Введите значение m:')))

import unittest, random
class Test_Account(unittest.TestCase):
    def test_random(self):
        Accountant.account(Accountant.calc(check, random.randint(0, 10), random.randint(0, 10)))
        self.assertEqual(Accountant().tr, Accountant().tc)
    def test_zero(self):
        Accountant.account(Accountant.calc(check, 0, 0))
        self.assertEqual(Accountant().tr, Accountant().tc)
    def test_max(self):
        Accountant.account(Accountant.calc(check, 10, 10))
        self.assertEqual(Accountant().tr, Accountant().tc)
    def test_regr(self):
        Accountant.account(Accountant.calc(check, 5, 5))
        self.assertEqual(Accountant().tr, Accountant().tc)
    def tearDownClass():
        Accountant.account(Accountant.calc(check, 0, 0))
if __name__ == '__main__':
    unittest.main(verbosity=2)
    • 0

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