知识问答

在__init__内调用类函数

内容 隐藏
问题：在__init__内调用类函数
回答 0
回答 1
回答 2
回答 3
回答 4
回答 5

问题：在__init__内调用类函数

我正在编写一些使用文件名，打开文件并解析出一些数据的代码。我想在课堂上做到这一点。以下代码有效：

class MyClass():
    def __init__(self, filename):
        self.filename = filename 

        self.stat1 = None
        self.stat2 = None
        self.stat3 = None
        self.stat4 = None
        self.stat5 = None

        def parse_file():
            #do some parsing
            self.stat1 = result_from_parse1
            self.stat2 = result_from_parse2
            self.stat3 = result_from_parse3
            self.stat4 = result_from_parse4
            self.stat5 = result_from_parse5

        parse_file()

但是，这涉及到我将所有解析机制置于__init__类的功能范围之内。现在，对于此简化的代码来说，这看起来还不错，但是该函数parse_file还具有许多缩进级别。我更喜欢将函数定义parse_file()为类函数，如下所示：

class MyClass():
    def __init__(self, filename):
        self.filename = filename 

        self.stat1 = None
        self.stat2 = None
        self.stat3 = None
        self.stat4 = None
        self.stat5 = None
        parse_file()

    def parse_file():
        #do some parsing
        self.stat1 = result_from_parse1
        self.stat2 = result_from_parse2
        self.stat3 = result_from_parse3
        self.stat4 = result_from_parse4
        self.stat5 = result_from_parse5

当然，此代码不起作用，因为该函数parse_file()不在函数范围内__init__。有没有办法从该类内部调用类函数__init__？还是我想这是错误的方式？

点击查看英文原文

I’m writing some code that takes a filename, opens the file, and parses out some data. I’d like to do this in a class. The following code works:

class MyClass():
    def __init__(self, filename):
        self.filename = filename 

        self.stat1 = None
        self.stat2 = None
        self.stat3 = None
        self.stat4 = None
        self.stat5 = None

        def parse_file():
            #do some parsing
            self.stat1 = result_from_parse1
            self.stat2 = result_from_parse2
            self.stat3 = result_from_parse3
            self.stat4 = result_from_parse4
            self.stat5 = result_from_parse5

        parse_file()

But it involves me putting all of the parsing machinery in the scope of the __init__ function for my class. That looks fine now for this simplified code, but the function parse_file has quite a few levels of indention as well. I’d prefer to define the function parse_file() as a class function like below:

class MyClass():
    def __init__(self, filename):
        self.filename = filename 

        self.stat1 = None
        self.stat2 = None
        self.stat3 = None
        self.stat4 = None
        self.stat5 = None
        parse_file()

    def parse_file():
        #do some parsing
        self.stat1 = result_from_parse1
        self.stat2 = result_from_parse2
        self.stat3 = result_from_parse3
        self.stat4 = result_from_parse4
        self.stat5 = result_from_parse5

Of course this code doesn’t work because the function parse_file() is not within the scope of the __init__ function. Is there a way to call a class function from within __init__ of that class? Or am I thinking about this the wrong way?

回答 0

以这种方式调用该函数：

self.parse_file()

您还需要像这样定义parse_file（）函数：

def parse_file(self):

该parse_file方法必须在调用时绑定到对象（因为它不是静态方法）。这是通过在对象的实例上调用函数来完成的（在您的情况下，实例是）self。

点击查看英文原文

Call the function in this way:

self.parse_file()

You also need to define your parse_file() function like this:

def parse_file(self):

The parse_file method has to be bound to an object upon calling it (because it’s not a static method). This is done by calling the function on an instance of the object, in your case the instance is self.

回答 1

如果我没记错的话，这两个函数都是您的类的一部分，则应像这样使用它：

class MyClass():
    def __init__(self, filename):
        self.filename = filename 

        self.stat1 = None
        self.stat2 = None
        self.stat3 = None
        self.stat4 = None
        self.stat5 = None
        self.parse_file()

    def parse_file(self):
        #do some parsing
        self.stat1 = result_from_parse1
        self.stat2 = result_from_parse2
        self.stat3 = result_from_parse3
        self.stat4 = result_from_parse4
        self.stat5 = result_from_parse5

替换行：

parse_file()

与：

self.parse_file()
点击查看英文原文

If I’m not wrong, both functions are part of your class, you should use it like this:

class MyClass():
    def __init__(self, filename):
        self.filename = filename 

        self.stat1 = None
        self.stat2 = None
        self.stat3 = None
        self.stat4 = None
        self.stat5 = None
        self.parse_file()

    def parse_file(self):
        #do some parsing
        self.stat1 = result_from_parse1
        self.stat2 = result_from_parse2
        self.stat3 = result_from_parse3
        self.stat4 = result_from_parse4
        self.stat5 = result_from_parse5

replace your line:

parse_file()

with:

self.parse_file()

回答 2

怎么样：

class MyClass(object):
    def __init__(self, filename):
        self.filename = filename 
        self.stats = parse_file(filename)

def parse_file(filename):
    #do some parsing
    return results_from_parse

顺便说一句，如果有一个名为变量stat1，stat2等等，情况正在乞求一个元组： stats = (...)。

因此，让我们parse_file返回一个元组，并将其存储在中 self.stats。

然后，例如，您可以访问曾经使用调用stat3的内容self.stats[2]。

点击查看英文原文

How about:

class MyClass(object):
    def __init__(self, filename):
        self.filename = filename 
        self.stats = parse_file(filename)

def parse_file(filename):
    #do some parsing
    return results_from_parse

By the way, if you have variables named stat1, stat2, etc., the situation is begging for a tuple: stats = (...).

So let parse_file return a tuple, and store the tuple in self.stats.

Then, for example, you can access what used to be called stat3 with self.stats[2].

回答 3

在中parse_file，接受self参数（与中一样__init__）。如果您需要任何其他上下文，则只需照常将其作为附加参数传递。

点击查看英文原文

In parse_file, take the self argument (just like in __init__). If there’s any other context you need then just pass it as additional arguments as usual.

回答 4

您必须像这样声明parse_file; def parse_file(self)。在大多数语言中，“ self”参数是一个隐藏参数，但在python中则不是。您必须将其添加到属于一个类的所有方法的定义中。然后您可以使用以下方法从类中的任何方法调用该函数self.parse_file

您的最终程序将如下所示：

class MyClass():
  def __init__(self, filename):
      self.filename = filename 

      self.stat1 = None
      self.stat2 = None
      self.stat3 = None
      self.stat4 = None
      self.stat5 = None
      self.parse_file()

  def parse_file(self):
      #do some parsing
      self.stat1 = result_from_parse1
      self.stat2 = result_from_parse2
      self.stat3 = result_from_parse3
      self.stat4 = result_from_parse4
      self.stat5 = result_from_parse5
点击查看英文原文

You must declare parse_file like this; def parse_file(self). The “self” parameter is a hidden parameter in most languages, but not in python. You must add it to the definition of all that methods that belong to a class. Then you can call the function from any method inside the class using self.parse_file

your final program is going to look like this:

class MyClass():
  def __init__(self, filename):
      self.filename = filename 

      self.stat1 = None
      self.stat2 = None
      self.stat3 = None
      self.stat4 = None
      self.stat5 = None
      self.parse_file()

  def parse_file(self):
      #do some parsing
      self.stat1 = result_from_parse1
      self.stat2 = result_from_parse2
      self.stat3 = result_from_parse3
      self.stat4 = result_from_parse4
      self.stat5 = result_from_parse5

回答 5

我认为您的问题实际上是没有正确缩进init函数，应该是这样的

class MyClass():
     def __init__(self, filename):
          pass

     def parse_file():
          pass
点击查看英文原文

I think that your problem is actually with not correctly indenting init function.It should be like this

class MyClass():
     def __init__(self, filename):
          pass

     def parse_file():
          pass