Developers Club geek daily blog

QThread + QtSql the right way

2 years, 9 months ago
Today's article inspired me to share the method of pronouncement of databases in separate rubs. The method is suitable not only for a DB, but also for any interactions described by a pattern "in a separate flow there lives some object, it is necessary to ask it something and with it to do something". Besides, the method is good the fact that he tries to be tipobezopasny and expanded: any stringly-typed QMetaObject::invokeMethod(), any transfers of results of yanking of object in a flow through signals. Only a direct call of functions, only QFuture!

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QThread + QtSql: Asynchronous requests

2 years, 9 months ago
When writing multithreaded applications on Qt many faced that implementation of QtSql strictly one-line. That it is worse, in it there is no uniform method for background execution of request. And if the request big or just long, execution it in the main flow tightly suspends the interface.

What irritates even more, there is no viable implementation of such, apparently, necessary thing anywhere. A maximum which can be found — the pool of connections working quite synchronously. Well, time passes, everything changes.

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As we automated unpacking of game

2 years, 9 months ago
My hobby, in addition to programming — development of modifications for the game S.T.A.L.K.E.R. We work in command where, as well as it is accepted, everyone is responsible for something special. I besides that I enter a circle of developers, also perform software development for command. Under a cat read how we automated unpacking of game archives what problems faced and as they were solved.

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Parallelization of algorithm of Shtrassen on Intel® Xeon Phi(TM)

2 years, 9 months ago
Intel Xeon Phi(TM) coprocessors represent PCI Express the device and have x86 architecture, providing high peak productivities — to 1,2 TFLOPS (one trillion operations with a floating comma per second) to double precision on the coprocessor. Xeon Phi(TM) can ensure simultaneous functioning to 244 flows, and it needs to be considered when programming for achievement of maximum efficiency.

Recently we together with the Intel company conducted small research of efficiency of implementation of algorithm of Shtrassen for the Intel Xeon Phi(TM) coprocessor. To whom subtleties of work with this device and simply loving parallel programming are interesting, I ask under kat.


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Conference C ++ Russia 2016, St. Petersburg

2 years, 9 months ago

Hi everyone!

On February 26-27, 2016 in St. Petersburg there will take place the conference, largest in Russia, devoted only to C ++. We tried to collect the best reports and to cover the most different subjects: from hardkorny korutin to an enterprayzny mokirovaniye, from creation of krash-contango before reactive programming. Besides, we will talk about boost, we will discuss what happens to standardization of parallel programming in C ++, we will consider some daily problems, for example, work with S-lines. This time we will try suit blitz reports again, but this time on them it is possible to be registered in advance (though now). There will be this year also something absolutely new.

Interestingly? Details under a cat!

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Python-> Cython-> C ++ and COM in addition: writing of a framework for autotests

2 years, 9 months ago
I think everything it is aware about advantage of autotests. They help to keep a code in operating state even at essential changes. Also it can relieve testers of tiresome handwork and allows to concentrate on more interesting types of testing.

In spite of the fact that to separate parts of our project more than 25 years, we only at the very beginning of a way of implementation of automatic testing. Nevertheless, we already have some progress of which I want to tell in this article.

How to write good autotests – a subject of separate article. And probably not one. I will tell you as we implemented testing of separate components. Components are written on With ++ and very similar to SOM have interfaces. As language for tests we selected python and we use very powerful test framework of PyTest. In article I will tell about difficulties of a linking of C++/COM and a python, reefs which we came across and as solved these problems.

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We mix colors correctly or we optimize AlphaBlend

2 years, 9 months ago
I write multilegal (but not multiplatform, alas, now only windows) a messenger which meanwhile supports only the TOX protocol. But the speech not about a messenger, and about its interface, and if more precisely, about its basic function — AlphaBlend. Yes, I decided to write the GUI bicycle. And what modern GUI without translucent elements and smooth curves? Therefore sharply there was a need to mix images taking into account translucency, i.e. alpha mixing or alpha blending. Fortunately, in the Windows GDI such function is available — AlphaBlend. Works as it is necessary, does what is necessary. But I that still the builder of bicycles, and it became interesting to me whether I will be able to write the same function, but faster. Result of my works under a cat.

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CrystaX NDK 10.3.0 is let out

2 years, 9 months ago
The new CrystaX NDK 10.3.0 version is available to downloading.

The most important changes in this release:

  • New GCC and LLVM/clang.
  • Support of Objective-C v2 is strongly improved.
  • Support of Python (2.7 and 3.5) for Android is added.


Besides, many errors are repaired and the huge number of improvements is made. Below you can study more detailed information.

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Marmalade C ++ and ShiVa3D: the beginning of work with game engines for the Android x86 platform

2 years, 9 months ago
You are engaged in development of the cross-platform application or game for Android? If so, then you have to look narrowly at special purpose tools. For example, to SDK Marmalade C ++ 8.0 and to the game ShiVa3D engine. Today we will talk about their application for the Android x86 platform.


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The self-modified code

2 years, 9 months ago
In article it is in detail told about self-modified a code (SMK), and about how to use it in the programs. Examples are written on C ++ with use of the built-in assembler. Still I will tell about how to execute a code on a stack that is an essential trump during the writing and execution of SMK.



1. Introduction


Well, went. Article promises to be long as I want to write it such that you had no questions. On SMK there are already one million articles, but my vision of a problem – after hundreds of hours of writing of SMK is provided here … I will try to push all the works here. Everything, be enough tomato juice (or that you prefer to drink there), do music louder and be going to learn how to relieve the application of the beginning crackers! In passing, I will tell you about memory of Windows and some other things about which you even do not suspect.

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