Python：将实例变量传递给class方法

Question

我正在使用 xlsxwriter 并且我创建了一个 class 并在其中创建了一个工作簿。然后我向其中添加了 2 个工作表。现在我已经编写了一种将数据写入其中一个工作表的方法，但现在我想在两个工作表上都使用它。这是一个简单的例子来说明情况：

import xlsxwriter

class ExcelWorkbook():
    def __init__(self, filename):
        self.wb = xlsxwriter.Workbook(filename)
        self.ws1 = self.wb.add_worksheet('Num')
        self.ws1LineCount = 0
        self.ws2 = self.wb.add_worksheet('Result')
        self.ws2LineCount = 0

    def write_data(self, data, title):        
        self.ws1.write_row(self.ws1LineCount, 0, title)
        self.ws1LineCount += 1
        self.ws1.write_row(self.ws1LineCount, 0, data)
        self.ws1LineCount += 1

xlsxWorkbook = ExcelWorkbook('Test2.xlsx')
numArr = (0.000000520593523979187, 13.123456789, 1.789456, 0.002345, 0.00123, 1)
titleBar = ('Date', 'quantity', 'Average [m]', 'Standard Dev [m]', 'Test', 'Success')
xlsxWorkbook.write_data(numArr, titleBar)

现在我想对两个工作表都使用 write_data 方法，所以我想我应该将工作表作为参数传递，但不幸的是，它并没有那么简单，因为我无法传递实例变量self.ws1 或 self.ws2.

所以问题是：我该怎么做？

我想到了一个非常糟糕的解决方案，像这样：

def write_data(self, data, title, instance = 'ws1'):
    if instance == 'ws1':
        instance = self.ws1
        lineCounter = self.ws1LineCount
    elif instance == 'ws2':
        instance = self.ws2
        lineCounter = self.ws2LineCount

    instance.write_row(self.ws1LineCount, 0, title)
    lineCounter += 1
    instance.write_row(self.ws1LineCount, 0, data)
    lineCounter += 1

但老实说我不喜欢它。有什么正确的做法吗，还是完全不合理的事情？

Answer 1

使用 vars(self)，您可以将对象的任何元素作为字典访问。

那么 vars(self)["ws1"] 就像 self.ws1 而 vars(self)["ws2"] 就像 self.ws2

然后你只需要在 write_data.

中传递一个关键参数 "ws1" 或 "ws2"

def write_data(self, data, title, key='ws1'):
    instance = vars(self)[key]
    lineCounter = vars(self)[key+"LineCount"]

    instance.write_row(lineCounter , 0, title)
    lineCounter += 1
    instance.write_row(lineCounter , 0, data)
    lineCounter += 1

Answer 2

我会这样做：

from collections import defaultdict
import xlsxwriter

class ExcelWorkbook():
    def __init__(self, filename):
        self.wb = xlsxwriter.Workbook(filename)

        self.ws1 = self.wb.add_worksheet('Num')
        self.ws2 = self.wb.add_worksheet('Result')
        self._line_counts = defaultdict(int)

    def write_data(self, ws, data, title):
        self._write_row(ws, title)
        self._write_row(ws, data)

    def _write_row(self, ws, content):
        ws.write_row(self._line_counts[ws], 0, content)
        self._line_counts[ws] += 1

xlsxWorkbook = ExcelWorkbook('Test2.xlsx')
numArr = (0.000000520593523979187, 13.123456789, 1.789456, 0.002345, 0.00123, 1)
titleBar = ('Date', 'quantity', 'Average [m]', 'Standard Dev [m]', 'Test', 'Success')
xlsxWorkbook.write_data(xlsxWorkbook.ws1, numArr, titleBar)
xlsxWorkbook.write_data(xlsxWorkbook.ws2, numArr, titleBar)

通过使用 defaultdict，您无需为每个工作表显式保留行数变量。 write_data 函数接受一个新参数 ws 以便您可以设置应写入的工作表。写一行可以分解成一个单独的方法来减少代码重复。

这是否回答了您的问题？

编辑：

默认值无法访问 self，但您可以很容易地解决此问题：

def write_data(self, data, title, ws=None):
        if ws is None:            
            ws = self.ws1
        self._write_row(ws, title)
        self._write_row(ws, data)

Answer 3

而不是 if 块，最好使用 workbook.get_worksheet_by_name() 方法

def write_data(self, data, title, ws = 'Num'):
    wsheet = self.wb.get_worksheet_by_name(ws)
    wsheet.write_row(self.ws1LineCount, 0, title)
    lineCounter += 1
    wsheet.write_row(self.ws1LineCount, 0, data)
    lineCounter += 1

编辑：或者您可以使用 getattr() 函数，例如

def write_data(self, data, title, ws = 'ws1'):
    wsheet = getattr(self, ws, self.ws1))
    wsheet.write_row(self.ws1LineCount, 0, title)
    lineCounter += 1
    wsheet.write_row(self.ws1LineCount, 0, data)
    lineCounter += 1

Answer 4

也许你应该考虑多一个class ExcelWorksheet，以便将所有相关的逻辑放在里面：

class ExcelWorksheet(object):
    def __init__(self, workbook, name):
        self.wb = workbook
        self.ws = self.wb.add_worksheet(name)
        self.wsLineCount = 0

    def write_data(self, data, title):        
        self.ws.write_row(self.wsLineCount, 0, title)
        self.wsLineCount += 1
        self.ws.write_row(self.wsLineCount, 0, data)
        self.wsLineCount += 1

这样，您可以将代码重构为：

class ExcelWorkbook(object):
    def __init__(self, filename):
        self.wb = xlsxwriter.Workbook(filename)
        self.ws1 = ExcelWorksheet(self.wb, 'Num')
        self.ws2 = ExcelWorksheet(self.wb, 'Result')


xlsxWorkbook = ExcelWorkbook('Test2.xlsx')
numArr = (0.000000520593523979187, 13.123456789, 1.789456, 0.002345, 0.00123, 1)
titleBar = ('Date', 'quantity', 'Average [m]', 'Standard Dev [m]', 'Test', 'Success')
xlsxWorkbook.ws1.write_data(numArr, titleBar)
xlsxWorkbook.ws2.write_data(numArr, titleBar)

Python：将实例变量传递给class方法

Python: passing instance variable to class method

python

python-2.7

xlsxwriter