使用getattr访问方法 [英] Accessing a method using getattr

问题描述

在创建新的类实例时，我试图在其他类中调用方法，但是无法使其正常工作.这就是我所拥有的:

When creating a new class instance, I'm trying to call a method in a different class however can't get it to work. Here's what I have:

class DataProject(object):    
    def __init__(self, name=none,input_file=None,datamode=None,comments=None,readnow=True):
        ..............
        # here's where I'm trying to call the method in the other class
        if type(input_file) == str:
            self.input_file_format = self.input_file.split(".")[-1]
            if readnow:
                getattr(Analysis(),'read_'+self.input_file_format)(self,input_file)

class Analysis(object):
    def __init__(self):
        pass # nothing happens here atm

    def read_xlsx(self,parent,input_file):
        """Method to parse xlsx files and dump them into a DataFrame"""
        xl = pd.ExcelFile(input_file)
        for s in sheet_names:
            parent.data[s]=xl.parse(s)

当我使用afile.xlxs作为输入运行此命令时，我得到一个NameError: global name 'read_xlsx' is not defined，这使我认为我刚刚发现了我的Python知识方面的一个巨大漏洞(不是虽然很多，但它们往往很难看，就像大片森林...).

I'm getting a NameError: global name 'read_xlsx' is not defined when I run this with afile.xlxs as input which made me think that I just discovered a massive hole in my Python knowledge (not that there aren't many but they tend to be hard to see, sort of like big forests...).

我本以为getattr(Analysis(), ... )将访问全局名称空间，在其中可以找到Analysis类及其方法.实际上print(globals().keys())表明Analysis是其中的一部分:

I would have thought that getattr(Analysis(), ... ) would access the global name space in which it would find the Analysis class and its methods. And in fact print(globals().keys()) shows that Analysis is part of this:

['plt', 'mlab', '__builtins__', '__file__', 'pylab', 'DataProject', 'matplotlib', '__package__', 'W32', 'Helpers', 'time', 'pd', 'pyplot', 'np', '__name__', 'dt', 'Analysis', '__doc__']

我在这里想念什么?

完整的回溯是:

Traceback (most recent call last):
  File "C:\MPython\dataAnalysis\dataAnalysis.py", line 101, in <module>
    a=DataProject(input_file='C:\\MPython\\dataAnalysis\\EnergyAnalysis\\afile.xlxs',readnow=True)
  File "C:\MPython\dataAnalysis\dataAnalysis.py", line 73, in __init__
    getattr(Analysis(),'read_'+self.input_file_format)(self,input_file)
  File "C:\MPython\dataAnalysis\dataAnalysis.py", line 90, in read_xls
    read_xlsx(input_file)
NameError: global name 'read_xlsx' is not defined

我的主要电话是:

if __name__=="__main__":
    a=DataProject(input_file='C:\\MPython\\dataAnalysis\\EnergyAnalysis\\afile.xlx',readnow=True)

推荐答案

从完整的追溯中看来，您的DataProject类正在(成功地)调用Analysys.read_xls方法，而该方法又试图调用.但是，它将其称为全局函数，而不是方法.

From the full traceback, it appears that your DataProject class is calling (successfully) the Analysys.read_xls method, which in turn is trying to call read_xlsx. However, it's calling it as a global function, not as a method.

也许您只需要替换第90行的代码，将read_xlsx(input_file)转换为self.read_xlsx(input_file)，尽管您可能还需要为父DataProject实例传递一个额外的参数.

Probably you just need to replace the code on line 90, turning read_xlsx(input_file) into self.read_xlsx(input_file), though you might need to pass an extra parameter for the parent DataProject instance too.

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