Python：将实例变量传递给类方法

Question

我正在使用xlsxwriter并且创建了一个在其中创建工作簿的类。 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，但是现在我想在两个工作表中都使用它。 这是一个简单的示例来说明这种情况：

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，我想在两个工作表中都使用write_data方法，因此我想将工作表作为参数传递，但是不幸的是，它不是那么简单，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？

我想出了一个非常讨厌的解决方案，例如：

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

但说实话我不喜欢 是否有适当的方法来做，还是完全不合理？

Answer 1

最好使用workbook.get_worksheet_by_name()方法代替if块

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 2

我会做这样的事情：

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函数接受新参数ws以便您可以设置应写入的工作表。 可以将写一行分解为一个单独的方法，以减少代码重复。

这回答了你的问题了吗？

编辑：

默认值不能访问self ，但是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

也许您应该考虑有一个额外的类ExcelWorksheet ，以便将与其相关的所有逻辑放入其中：

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)

Answer 4

使用vars（self），您可以作为字典访问对象的任何元素。

然后vars（self）[“ ws1”]就像self.ws1，而vars（self）[“ ws2”]就像self.ws2

然后，您只需要在write_data中传递键参数“ 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