Let's take a look at a small code example when a method is called on an object that is initialized with nullptr .

This article is the most comprehensive description of signals and slots in QML compared to all previous articles on this site.

In this article, I will try to explain the following when working with Qt/QML + Qt/C++:

• ways to declare signals and slots, also called methods in the C ++ class, which will be registered in the QML layer
• ways to connect to signals of classes declared in C ++ as context
• work with Q_PROPERTY, which also requires signals and slots
• ways to connect signals and slots in QML
• etc.

I propose to consider the option of using variables declared in the CMakeLists.txt file in C ++ code.

To begin with, what is it for? For example, you want to specify the version of the program and some other auxiliary information that is set during the assembly of the program, but at the same time you want to use this information in your C ++ code? Is it possible to do this? For example, to make it look like the image shows.

A small note about static linking Boost, so as not to forget.

Initial data:

• OS Windows
• MSVC 2017 64bit
• Boost 1.68.0
• CMake project

An example will be shown in the simplest version without special variable settings. Maximum default.

Let's write a small example of an application in which a button will be moved using property animations. To do this, we use the QSequentialAnimationGroup and QPropertyAnimation classes.

QSequentialAnimationGroup is a class that combines several animations into one group, which allows you to automatically start one animation when the previous QPropertyAnimation has completed.

Animation will be launched by pressing the button and this button will move in the window as shown in the image.

And here is an article on the boost of my some accumulated materials. I offer you the option of writing a console program with support for the console menu, which is implemented using boost::program_options .

boost::program_options is responsible for processing the arguments passed to the program and sets all the necessary variables without the need to implement long logic from if else branches. This is already implemented inside boost::program_optons .

Suppose our program takes the following data as arguments

• input file path
• output file path
• the size of the block being processed, no matter why, we will not do anything with it, just have such a parameter in the program.

Also, the program will have a help menu, which will be the console menu.

The figure below shows the use of this program.

Start at work to use a compiler that supports the standard C++17.

Actively we begin to use various features from this standard..

I was pleased with the [[fallthrough]] attribute for switch case constructions.

Discussion. The forte of Builder is constructing a complex object step by step. An abstract base class declares the standard construction process, and concrete derived classes define the appropriate implementation for each step of the process. In this example, "distributed work packages" have been abstracted to be persistent and platform independent.

This means that the platform-specific mechanism for implementing files, queues, and concurrency pathways is defined in each platform's concrete derived class. A single "reader" object (i.e. parser) retrieves the archived specification for a DistrWorkPackage and proceeds to delegate each build step to the builder object that was registered by the client. Upon completion, the client retrieves the end result from the builder.

Цели

• Определяем интерфейс для создания объекта, но пусть подклассы решают, какой класс следует создавать. Фабричный метод позволяет создать экземпляр класса для подклассов.
• Определение «виртуального» конструктора.
• Оператор new является вредным.

Проблематика

Структура проекта должна стандартизировать архитектурную модель для целого ряда приложений, но позволяет отдельным приложениям определять свои собственные объекты и обеспечивать собственные правила их создания при сохранении единообразного интерфейса создания объектов.

Обсуждение. «Подумайте о создании объектов как о фабрике, которая порождает эти самые объекты».

Здесь мы назначаем обязанности создания объектов фабричному объекту, а затем используем функции наследования и виртуальные члены для предоставления возможности «виртуального конструктора». Таким образом, существуют два аспекта. Клиент использует фабричный объект вместо оператора «new» для запроса создания экземпляров; и клиент имеет «жесткую привязку» к семейству или классу этой фабрики, и на протяжении всей работы приложения полагается на абстрактный базовый класс.