How to free the memory usage of a qwidget?

Mr Pang

I have a simple example

#ifndef TXTEDITOR_H
#define TXTEDITOR_H

#include <QWidget>

namespace Ui {
class TxtEditor;
}

class TxtEditor : public QWidget
{
    Q_OBJECT

public:
    explicit TxtEditor(QWidget *parent = 0, QString file = "");
    ~TxtEditor();

private:
    Ui::TxtEditor *ui;
};

#endif // TXTEDITOR_H

#include "txteditor.h"
#include "ui_txteditor.h"
#include <QPlainTextEdit>
#include <QTextStream>


TxtEditor::TxtEditor(QWidget *parent, QString file) :
    QWidget(parent),
    ui(new Ui::TxtEditor)
{
    ui->setupUi(this);
    QPlainTextEdit *editor = ui->plainTextEdit;
    QFile f(file);
    if(f.open(QIODevice::ReadOnly|QIODevice::Text)){
        QTextStream  in(&f);
        editor->setPlainText(in.readAll());
    }
}

TxtEditor::~TxtEditor()
{
    delete ui;
}

I use it as

TxtEditor *editor = new TxtEditor(NULL,"/boot/System.map-4.3.3");
    editor->show();

I want to free all the memory used by editor when I close the editor window.
How to do that?

Mr Pang

overload

void TxtEditor::closeEvent(QCloseEvent *)
{
    deleteLater();
}

Is this OK？

ValentinMichelet

@Mr-Pang
Where do you create your TxtEditor? Can't it have a parent widget?
If you can set your widget a parent, then let Qt mechanisms handle the proper deletion for you.
Maybe you can consider creating your TxtEditor on the stack, depending on your scope.

Mr Pang

overload closeEvent seems to work.

Chris Kawa

There's an attribute specifically for that purpose:

TxtEditor *editor = new TxtEditor(nullptr, "/boot/System.map-4.3.3"); //you should really put "parent" as last param
editor->setAttribute(Qt::WA_DeleteOnClose);