I cloned QT repository:
git clone --recursive https://code.qt.io/qt/qt5.git --branch v6.2.0
cd qt5
Looks like the command below is not required:
./init-repository --module-subset=all
because it prints:
Will not reinitialize already initialized repository (use -f to force)!
Looks like QtPurchasing uses deprecated AIDL billing library and people say that it crashes on some devices. See https://developer.android.com/google/play/billing/deprecation-faq for more information. Probably they are going to update it in 5.15.7 and move it into examples in QT 6, so it is not clear exactly what will happen with it, we probably better wait QT 5.15.7 to be released.
(more…)Put the header content into a text file and load it into a variable:
cd ~/temp/
nano h.txt
h=$(<h.txt)
In C++20 we can do this:
#include <ranges>
#include <vector>
template <std::ranges::range Range>
requires std::same_as<std::ranges::range_value_t<Range>, int>
auto TransformIt(Range r)
{
return r | std::views::transform([](int n) { return n * n; });
}
int main()
{
std::vector<int> v;
auto r = TransformIt(v);
return 0;
}
The program below is terminated when the deleter throws the exception:
#include <iostream>
#include <memory>
struct X
{
int value;
};
struct Deleter
{
void operator()(X* p) noexcept(false)
{
if (p->value == 0)
{
throw std::logic_error("Can't delete a zero.");
}
delete p;
}
};
In QT 5.15 I declare a class with an invokable constructor:
class TestClass : public QObject
{
Q_OBJECT
public:
Q_INVOKABLE TestClass(QString val) {}
};
Q_DECLARE_METATYPE(TestClass*)
register its type:
qRegisterMetaType<TestClass*>();
std::unordered_set has a template find function in C++20. To make it work I define a custom hash and a custom equality compares as follows:
struct BotSettings
{
std::string type;
std::string name;
bool started;
};
I used a simple algorithm a got an interesting effect: the bot often buys at the peaks of the falling price. Below I provided some examples of buying the cryptocurrency on Binance crypto exchange:
DASH/USDT:
I get close reason: ‘Invalid UTF-8 code encountered.’ (code=1007) with QWebSocket in the following scenario:
Binance stream wss://stream.binance.com:9443/stream with QWebSocket::open.Binance disconnects me when its servers load increases (because I have low-priority API) and I get close reason code=1000 that indicates a normal closure.QWebSocket::open again, but Binance closes the connection with close reason ‘Invalid UTF-8 code encountered.’ (code=1007) that indicates that an endpoint is terminating the connection because it has received data within a message that was not consistent with the type of the message (e.g., non-UTF-8 [RFC3629] data within a text message).The difficulty of reproducing the bug is that Binance disconnects me rarely (once a day, for example) and experimentation with disconnecting the network cable from my machine does not have this effect, after I connect the cable back, QWebSocker reconnects successfully. When I disconnect the network cable I get Error: ‘Unknown error’ (code=-1), Close reason: ” (code=1000).
