class

问题 I have a class like this: class A { protected: int t = 10; public: void f() { struct B { void g() { print(t); //using t } }; B b; b.g(); } }; ERROR: a nonstatic member reference must be relative to a specific object I see, members of class A is not visible in struct B (which is inside class A method). But how I may capture they, or make friends A and B? (If it's possible) 回答1: Defining B inside a method of A does not make instances of A contain a B . No matter where you define a class, you

问题 plan im sure this question must have been answered somewhere because its pretty basic, but unfortunately I havent found the answer ... My plan is to create a simple log function that uses a RichTextField as an output and implements functionalities like Add, AddLine, RemoveLine, ReplaceLine, ... what doesnt work whenever i try to access the RichTextBox object from within the log Class, i get a "is nothing" exception. my approach the idea was to store a reference to the RichTextBox in the class

问题 I think this is more of a python question, then a kivy question. class Keyboard is sharing a method from class GUI. I created an GUI instance called "self.a" to connected the 2 classes in class Keyboard. Also, I created a keyboard class instance, "self.key in class MainApp. when I use this method, "print ("Return button is pressed")" the "return" button was able to do the print statement. I understand why it works. When I use the "self.a.up()" in the method, the return button does not called

问题 This question already has an answer here : ES6 Object Destructuring Default Parameters (1 answer) Closed 2 years ago . Context: this is a task in a javascript tutorial. The code is supposed to generate a subclass ExtendedClock of Clock that allows the console to show the current time in a customized interval of time. Class Clock { constructor({ template }) { this._template = template; } _render() { let date = new Date(); let hours = date.getHours(); if (hours < 10) hours = '0' + hours; let

问题 I have parent class and child class, that inherits parent class. And that is okay, I can iterate with for loop. Now I want to access child class (example: 'product_type' So basically, I'm confused how we inherits stuff from child class inside the same loop... views.py from django.views import generic from . models import Category from django.shortcuts import render class CategoryListView(generic.ListView): model = Category template_name = 'category_list.html' models.py from django.db import

问题 when I tried to compile the following code I got an error: "include/IBCppClient/client/SoftDollarTier.h|3|error: variable ‘TWSAPIDLLEXP SoftDollarTier’ has initializer but incomplete type|". I guess the code is correct since it is part of a stock broker's API. But I struggle to understand the part on class definition "class TWSAPIDLLEXP SoftDollarTier" . As far as I know, this syntax is not legal in C++. What did I miss? class TWSAPIDLLEXP SoftDollarTier{ std::string m_name, m_val, m

问题 Got this: import pandas as pd from df import df import matplotlib as plt import seaborn as sns class Data_load: def __init__(self, df): self.df = pd.read_csv(df, delimiter=';') # Data information section def get_EDA_columns(self): return self.df.columns def get_EDA_info(self): return self.df.info() def get_EDA_describe(self): return self.df.describe() def get_EDA_shape(self): return self.df.shape def get_EDA_value_counts(self): return self.df.value_counts() def get_EDA_isnull(self): return

问题 I have a small piece of code, which was working fine, until I decided to create a class and put things into that class. Now my problem is, I cannot change stringvariable anymore. Here is my code: import tkinter as tk import tkinter.ttk as ttk class MainApplication(tk.Frame): def __init__(self, parent, *args, **kwargs): tk.Frame.__init__(self, parent, *args, **kwargs) self.parent = parent frame1 = ttk.LabelFrame(root, text="PANEL A", borderwidth=5) frame1.grid(row=0, column=0, padx=5, pady=5)

问题 I have a class named StrucData in subfile.py class StrucData: def __init__(self, name): self.name=name def loadData(self, size=1, cost=1): self.size=size self.cost=cost In the main file I: call the subfile, create a list of data names loop through the list to instantiate the objects; and load data using 'loadData' method for each object (I'm using the same 'size' and 'cost' to make this example easy.) from subfile import StrucData listIndex=['data1','data2','data3'] # Create a list of objects

问题 I am currently having a model: class Current(models.Model): field1 = models.IntegerField() field2 = models.IntegerField() field3 = models.IntegerField() I need to have field3 to be set directly equal to field1 + field2 without actually sending it. What's the standard way in django to do this? PS: Yes, I need to save field3 in the database alongwith the other fields. 回答1: Something like this? But not sure why this would need to be saved in the database. class Current(models.Model): field1 =