Python init self master

Your Application class is a subcategory of tk.Frame and has an optional parent widget parameter ( master ). If unspecified, none will be used as the default value for this parameter. This parameter will be supplied to the newly created instance of the Application class during initialization.

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How to properly define a class object in tkinter

As part of my Python3 learning, I am currently working on creating a canvas that consists of an oval and a button. My aim is to enable the oval's width to increase upon clicking the button. Although the button and oval are displaying correctly, clicking the button does not yield the desired outcome and instead generates error message error message.

Exception in Tkinter callback Traceback (most recent call last): File "C:\Users\amjones20\AppData\Local\Programs\Python\Python36-32\Lib\tkinter\__init__.py", line 1699, in __call__ return self.func(*args) File "C:/Users/amjones20/PycharmProjects/gui/guiPractice1.py", line 13, in oval_change Canvas.itemconfigure(self, oval, width=3) NameError: name 'oval' is not defined 

The oval_change function doesn't seem to acknowledge self.oval in the __init__ function. Defining oval correctly is crucial for its recognition when the oval_change function is invoked. The code is provided below.

from tkinter import * class GUI(Canvas): def __init__(self, master): self.canvas = Canvas(master, width=600, height=600) self.canvas.pack() self.oval = self.canvas.create_oval(100,500,500,100) def oval_change(self): Canvas.itemconfigure(self, oval, width=3) def button_appear(self): self.button1 = Button(root, text="button", command=self.oval_change) self.button1_window = self.canvas.create_window(200, 200, window=self.button1) root = Tk() hex = GUI(root) hex.button_appear() root.mainloop() 

Let me clarify that this issue is not related to tkinter. The initialization rules for tkinter classes are similar to those for any other python class.

class GUI(Canvas): def __init__(self, master): self.canvas = Canvas(master, width=600, height=600) self.canvas.pack() 

A class is being defined which is inherited from Canvas , however, the constructor of the superclass is not being called properly resulting in incomplete construction.

You are creating a new canvas within the existing canvas.

As your custom class is already a Canvas , there is no requirement to produce an additional canvas. All you have to do is initialize the class appropriately and use the instance itself to construct the oval.

class GUI(Canvas): def __init__(self, master): Canvas.__init__(self, master, width=600, height=600) self.oval = self.create_oval(100,500,500,100) 

The error message indicates name 'oval' is not defined because you're only generating self.oval and not oval . To resolve this issue, apply self.oval instead. Moreover, it's preferable to invoke the method on self instead of the class.

def oval_change(self): self.itemconfigure(self.oval, width=3) 

The responsibility of placing the canvas in the window should lie with the code that creates it, eventually.

hex = GUI(root) hex.pack(fill="both", expand=True) 

Here is the complete program:

from tkinter import * class GUI(Canvas): def __init__(self, master): Canvas.__init__(self, master, width=600, height=600) self.oval = self.create_oval(100,500,500,100) def oval_change(self): self.itemconfigure(self.oval, width=3) def button_appear(self): self.button1 = Button(self, text="button", command=self.oval_change) self.button1_window = self.create_window(200, 200, window=self.button1) root = Tk() hex = GUI(root) hex.pack(fill="both", expand=True) hex.button_appear() root.mainloop() 

Interacting with the Master Page from the Content Page, Open the Site.master master page and add a Label and a GridView control to the leftContent

Grails: how to define a master-detail view with grails constraints

My goal is to establish a basic view that showcases the master/detail relationship between the following tables:

create table MASTER_ID2 ( ID int not null, VALOR varchar(40), primary key (ID) ); create table DETAIL_ID2 ( ID int not null, ID_MASTER int not null, VALOR_DET char(40), primary key (ID) ); alter table DETAIL_ID2 add constraint FK_RDET5 foreign key (ID_MASTER) references MASTER_ID2 (ID) on delete restrict on update restrict; 

I have these domain classes:

class MasterId2 < Integer id String valor // static hasMany = [details : DetailId2] static mapping = < table 'master_id2' version false id generator:'identity', column:'ID' // details column: 'id_master' >static constraints = < id(max: 2147483647) valor(size: 0..40) >String toString() < return "$" > > class DetailId2 implements Serializable < Integer id Integer id_master String valor_det // MasterId2 master static belongsTo = MasterId2 static mapping = < table 'detail_id2' version false id generator:'identity', column:'ID' >static constraints = < id(max: 2147483647) valor_det(size: 0..40) >String toString() < return "$" > > 

However, the detail view fails to allocate a foreign key.

Integer id String valor // static hasMany = [details : DetailId2] static mapping = < table 'master_id2' // version is set to false, because this isn't available by default for legacy databases version false id generator:'identity', column:'ID' // details column: 'id_master' 

static constraints = < id(max: 2147483647) valor(size: 0..40) >String toString() < return "$" > 

The Serializable interface is implemented by the DetailId2 class.

Integer id Integer id_master String valor_det // //MasterId2 master //static belongsTo = MasterId2 static belongsTo = [master: MasterId2] static mapping = < table 'detail_id2' // version is set to false, because this isn't available by default for legacy databases version false id generator:'identity', column:'ID' // master insertable: false // enforce foreign key master updateable: false // enforce foreign key 

static constraints = < id(max: 2147483647) valor_det(size: 0..40) >String toString() < return "$" > 

Listbox without any values under the Master category.

Alter the mapping for DetailId2.

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Class with an unordered set of itself

In essence, I am wondering if it's possible to generate a class that contains a unordered set with a template type that is the class itself. To illustrate, suppose I want to create a Square class with a reference to an unordered set of adjacent squares. However, I encountered a difficulty when attempting to incorporate a hash function into the class definition. Below is the code I have so far.

#include #include #define SIZE 200 #define MASTER 0 class Square; namespace std < template<>struct hash  < std::size_t operator () (Square const &v) const < return v.r; >>; > class Square < public: int c1, c2; int r; std::unordered_set*neigh; Square() < neigh = new std::unordered_set(); > ~Square() < delete neigh; >bool operator==(const Square& second) < return this->r == second.r && this->c1 ==second.c1 && this->c2 == second.c2; > >; int main(int argc, char *argv[]) < Square sq; Square tt; sq.neigh->insert(tt); > 

Attempts were made to compile with g++ and FLAGS = --std=c++17 -Wall -Wextra -Wno-unused-parameter -Wno-unused-variable -ggdb, but a vast error message ensued, commencing with:

test.cpp: In member function ‘std::size_t std::hash::operator()(const Square&) const’: test.cpp:15:20: error: invalid use of incomplete type ‘const class Square’ 15 | return v.x; 

Uncertainty clouds my judgment on the appropriate course of action for this scenario. It is worth noting that the code presented is a simplified version of my requirements, yet the inclusion of a "neighbors" field is crucial.

To address your inquiry, simply define std::hash::operator() before the Square declaration without executing it.

namespace std < template<>struct hash < std::size_t operator() (Square const &) const; >; > 

Following the definition of Square , proceed to define std::hash::operator() .

namespace std < std::size_t hash::operator() (Square const& v) const < // return calculation >> 

In addition to the issue with insert , it seems that duplicating an object with a pointer and then deleting the same pointer twice is causing a problem. To fix this, consider using std::unique_ptr> as it will generate a compilation error if an attempt is made to copy it.

class Square< public: std::unique_ptr> neigh; Square() : neigh()> <> // no destructor needed bool operator==(const Square& second) const < // should be const // . >>; 

sq.neigh->emplace(. constructor arguments. );