marcelpetrick

Win: run script after executing the VisualStudio-environment-command

Written by  on July 11, 2019

Problem: our CMakeLists.txt contained one specific variable which is just set via the VisualStudio-command-prompt. But I did not want to start that cmd, then execute our “start IDE”-script from there. Naa, too much clicks 😉
Copy this as bat-file to the directory where the qtcreator.bat would be.

python: maximum size of certain containers

Written by  on July 9, 2019

Getting the 64 bit version is quite important. Still don’t get it why for Win the 32 bit one was preferred ..

32 bit: 2147483647 (elements)
64 bit: 9223372036854775807 (elements)

20190711 edit: even if the container could keep that much elements – remember that [Boolean] is 24 Byte (intead of one Bit) in vanilla Python. Means: if you run out of real memory, then MemoryError :/

Education 2019

Written by  on June 27, 2019

Time to reveal the plans of the supervised education for 2019: today my course from the “Volkshochschule” (adult evening school?) for “machine learning with Python” starts (you remember the course for advanced Python I did in May 2018 and which I backep up by doing exercises for Project Euler and “365 days coding challenge”? link ). I am really, really looking forward and am eager to learn 🙂

After this is finished in June my course for basic introduction to Mandarin will start (not a ‘computer’ language, but an interesting one) in addition to my daily Duolingo-exercises for this upcoming lingua franca (from my POV). Will be a challenge, especially the spoken version with its intonations.

Last but not least: on week ago I participated in a course as first responder for emergencies (at work).

And I still plan to do a professional certified course for software architecture (the big picture) in autumn.

edit: repo with a apart of the notes from the machine learning with Python-course are at Github.

Heltec WifiKit 8

Written by  on June 11, 2019

Ordered myself two Wifikit8 Esp8266-based boards from Aliexpress.
Received them after roundabout two weeks and now the fun can start.

With the integrated 0.91″ display (128×32 Pixel) a lot of effort for integrating some display or LEDs can be saved. Just noticed that a LiPo-charger is built-in as well, wow. For 4,50 € not a bad choice. But I am not 100% sure if this is the real device or some copycat – nevertheless: in the end the functionality matters.

First project-idea is to create an extended and verifyable version of the random-reviewer. With display of the currently chosen person, a big buzzer-button as trigger and a web-interface for those who doubt the true randomness ..

good guides:

Qt: clean includes

Written by  on May 20, 2019

(I’ve decided to follow a more agile workflow: instead of creation a “one post covers the whole topic”-post, to post also updates for each step. Article will be therefore edited while “doing”)

Last week I’ve cleaned Qt-includes for a larger project. Like #include to #include how it should be. With proper indirection, so that the Qt-library handles how and where the class is implemented.
A colleauge raised the question, why not use #include to be even more precise and to see the used module directly (needed for the CMakeLists or qmake).

First step: identify all used Qt-includes

Greps all includes starting with an uppercase Q; then split the result at the “:”; then sort und make it unique

Second step: create a replacement-list and a (python?) script which does this for all .h/.cpp-files
tdb

C++: proper init for double/float and the proper check

Written by  on May 9, 2019

Problem was that I initialized some doubles with 0.0 and then hoped that the imported values are assigned, which does not happen always. So a check was needed. But checking if(0.0 == x) is a really bad idea. MinGW will tell you too (as other compilers).
So I was searching for a proper way to check against 0.0. And then I found a better idea: initialize with NaN and use the standard-check against this. Much better!

(addendum: I know, a variant would be the best to fix the given task.)

I want my Wifi-repeater. Now!

Written by  on May 4, 2019

Three weeks ago, while being in the garden, I noticed that there is no network connectivity except by superslow EDGE. Of course, three walls block the Wifi-router, but what about one repeater which is closer and just shielded by one wall? Also I remembered having read about the usage of some ESP-nodes for that. I don’t like the approach of buying some closed-source-product.

Short research yielded the project from martin-ger on Github, which I wanted to use. I was surprised that nothing for the ESP32 is available (only for ESP8266). So I tracked down my single ESP8266 (LoLin, NodeMCU, not sure which revision, but with CH340G-USB-connect and as DevKit (mingling with pulldown-resitors would add another layer of complexity, which I am not sure I want to tackle).
Turns out I could not flash the given item properly with the ESP8266 Download Tool 3.65. It blinks while doing so, but follow-up seral-monitoring onyl yields “lolin ts Jan 8 2013,rst cause:2, boot mode:(3,6)”.

So I ordered a from a german shop a new ESP8266. Looks like exactly the same model.
Will do some quicktest now with the blink-app (basic functionality and flashing works?). And then do a test with the ESP Download tool.

More later ..

Advanced debugging: find call which triggers Qt-errors

Written by  on April 26, 2019

Currently the debugging version of the Qt-libraries is not available. But I receive a report "QIODevice::write (QIODevice): Called with maxSize < 0" deep within them.
Our codebase is quite large, I am more familiar with other sections and let's say it: some is 'legacy'. So, where to start looking?!?
Yesterday I remembered a trick to get via call-stack to the last-recent position where our functions trigger that mistake.

Inserted in the main.cpp after show from the MainWindow was called a

which stands for this

Add a breakpoint in the messageHandler and debug the app. Maybe disable the breakpoint until you start to trigger the critical functionality.
When it breaks, you have a nice callstack and can backtrace where it came from :)

how to resume broken downloads

Written by  on April 24, 2019

aka: fix the weird firewalling settings ..
aka: How to download the latest stable Qt SDK source code?
curl -L -O -C - http://download.qt.io/official_releases/qt/5.12/5.12.3/single/qt-everywhere-src-5.12.3.zip

cmd replacement: cmder

Written by  on March 29, 2019

Sometimes you have to call some batch-files with spoecific windows-tools, so a bash is not helpful on Win.
A colleague recommended cmdr, which is quite nice and fine.
Suits my needs 🙂