“自己"是什么时候必需的? [英] When is "self" required?

问题描述

我使用类的时间很短，当我编写一个方法时，我让所有变量都引用 self，例如self.foo.

I have been using classes for only a short while and when I write a method, I make all variables reference self, e.g. self.foo.

然而，我正在阅读 wxPython in Action 一书，注意到self"并没有一直使用.例如:

However, I'm looking through the wxPython in Action book and notice that "self" isn't used all the time. For example:

 import wx
 class TextFrame(wx.Frame):
    def __init__(self):
        wx.Frame.__init__(self, None, -1, 'Text Entry Example',
            size=(300, 100))
        panel = wx.Panel(self, -1)
        basicLabel = wx.StaticText(panel, -1, "Basic Control:")
        basicText = wx.TextCtrl(panel, -1, "I've entered some text!",
            size=(175, -1))
        basicText.SetInsertionPoint(0)
        pwdLabel = wx.StaticText(panel, -1, "Password:")
        pwdText = wx.TextCtrl(panel, -1, "password", size=(175, -1),
            style=wx.TE_PASSWORD)
        sizer = wx.FlexGridSizer(cols=2, hgap=6, vgap=6)
        sizer.AddMany([basicLabel, basicText, pwdLabel, pwdText])
        panel.SetSizer(sizer)

下面的那个确实使用了self".

The one below does use "self".

import wx
class ButtonFrame(wx.Frame):
    def __init__(self):
        wx.Frame.__init__(self, None, -1, 'Button Example',
            size=(300, 100))
        panel = wx.Panel(self, -1)
        self.button = wx.Button(panel, -1, "Hello", pos=(50, 20))
        self.Bind(wx.EVT_BUTTON, self.OnClick, self.button)
        self.button.SetDefault()
    def OnClick(self, event):
        self.button.SetLabel("Clicked")

如果我没记错的话，self"是对类的特定实例的引用，那么什么时候不需要呢?是否有一般的经验法则?

If I remember correctly, "self" is reference to a particular instance of the class, so when is it not necessary? Is there a general rule of thumb?

推荐答案

您使用 self.attribute 来引用当前实例的属性.

You use self.attribute to reference an attribute of your current instance.

您使用 wx.Frame.__init__() 来引用父类的方法.

You use wx.Frame.__init__() to reference a method of the parent class.

如果您只引用您所在的方法(函数)的本地名称(变量)，则不要使用 self.

You don't use self if you only reference a local name (variable) of the method (function) you are in.

这些不是经验法则"，因为没有例外.

These are not "rules of thumb," because there are no exceptions.

在这个特定示例中可能让您感到困惑的是，面板似乎只是构造函数中的一个本地名称，因此一旦您的构造函数返回，面板就会消失.

What is probably confusing you in this particular example is that panel seems to be only a local name in the constructor, so it looks like the panel would disappear, once your constructor returns.

如果您查看wx.Panel 的文档，您会看到它的 构造函数将面板附加到父窗口，因此它将继续存在, 即使在构造函数返回之后.

If you look at the documentation to wx.Panel, though, you will see that its constructor attaches the panel to the parent window, so it will continue to exist, even after the constructor returns.

魔法:)

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