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I fixed this by adding the following:
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to Nginx configuration.
(more…)Category Archives: Programming languages
An example where we need const_cast in C++
class Example
{
public:
Example()
{
m.emplace("abc", 13);
}
const int& findValue(const std::string& val) const
{
auto i = m.find(val);
if (i == m.end()) {
throw std::runtime_error(std::format("Key {} not found.", val));
}
return i->second;
}
int& findValue(const std::string& val)
{
return const_cast<int&>(
const_cast<const Example*>(this)->findValue(val));
}
An Interface Segregation Principle (ISP) example
#include <iostream>
#include <memory>
#include <string>
#include <vector>
struct IObject {
virtual ~IObject() = default;
/// Returns the name of the object.
virtual std::string getName() const = 0;
/// Prints a textual description of the object.
virtual void describe() const = 0;
/// Eats another object.
virtual bool eat(IObject* other) = 0;
};
An investigation of why dynamic_cast violates LSP
Signal sender cast in QT
QT implies that the client code will do qobject_cast that is actually dynamic_cast:
awl::ProcessTask<void> MarketModel::coPlaceOrder(OrderPtr p)
{
// Update SQLite databse...
// ...
// QT signals are used in both C++ and QML.
// They works with QObject*, and they are not aware of concrete types.
QObject::connect(p.get(), &OrderModel::statusChanged, this, &MarketModel::onOrderStatusChanged);
}
Examples of const function parameters in C++
Examples with int
Compiles without warnings with MSVC:
class A
{
public:
void f(const int a);
};
void A::f(int a)
{
a = 10;
std::cout << a;
}
Investigating cobalt::generator
Standard C++ generator
The code below demonstrates how standard C++23 synchronous generator works:
#include <boost/cobalt.hpp>
#include <iostream>
#include <generator>
namespace cobalt = boost::cobalt;
std::generator<int> numbers()
{
for (int i = 1; i <= 5; ++i)
{
co_yield i;
}
}
Building boost::cobalt with MSVC 2022
cd C:\dev\repos\boost_1_89_0
set OPENSSL_ROOT_DIR=C:/dev/libs/OpenSSL
set OPENSSL_USE_STATIC_LIBS=ON
bootstrap.bat
b2 cxxstd=20 install --with-system --with-thread --with-cobalt --prefix=C:/dev/libs/boost_1_89_0 --toolset=msvc-14.3 -s _WIN32_WINNT=0x0A00 link=static runtime-link=static variant=release address-model=64
b2 cxxstd=20 install --with-system --with-thread --with-cobalt --prefix=C:/dev/libs/boost_1_89_0 --toolset=msvc-14.3 -s _WIN32_WINNT=0x0A00 link=static runtime-link=static variant=debug address-model=64
Using Frida to hook Win API calls
python -m pip install frida-tools
Collecting frida-tools
Downloading frida-tools-14.4.5.tar.gz (4.7 MB)
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 4.7/4.7 MB 2.8 MB/s 0:00:01
Installing build dependencies ... done
Getting requirements to build wheel ... done
Preparing metadata (pyproject.toml) ... done
Requirement already satisfied: colorama<1.0.0,>=0.2.7 in c:\dev\tools\python313\lib\site-packages (from frida-tools) (0.4.6)
Collecting frida<18.0.0,>=17.2.8 (from frida-tools)
Downloading frida-17.2.17-cp37-abi3-win_amd64.whl.metadata (2.3 kB)
Collecting prompt-toolkit<4.0.0,>=2.0.0 (from frida-tools)
Downloading prompt_toolkit-3.0.52-py3-none-any.whl.metadata (6.4 kB)
Collecting pygments<3.0.0,>=2.0.2 (from frida-tools)
Downloading pygments-2.19.2-py3-none-any.whl.metadata (2.5 kB)
Collecting websockets<14.0.0,>=13.0.0 (from frida-tools)
Downloading websockets-13.1-cp313-cp313-win_amd64.whl.metadata (7.0 kB)
Collecting wcwidth (from prompt-toolkit<4.0.0,>=2.0.0->frida-tools)
Downloading wcwidth-0.2.13-py2.py3-none-any.whl.metadata (14 kB)
Downloading frida-17.2.17-cp37-abi3-win_amd64.whl (41.8 MB)
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 41.8/41.8 MB 10.6 MB/s 0:00:04
Downloading prompt_toolkit-3.0.52-py3-none-any.whl (391 kB)
Downloading pygments-2.19.2-py3-none-any.whl (1.2 MB)
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 1.2/1.2 MB 10.4 MB/s 0:00:00
Downloading websockets-13.1-cp313-cp313-win_amd64.whl (159 kB)
Downloading wcwidth-0.2.13-py2.py3-none-any.whl (34 kB)
Building wheels for collected packages: frida-tools
Building wheel for frida-tools (pyproject.toml) ... done
Created wheel for frida-tools: filename=frida_tools-14.4.5-py3-none-any.whl size=4699595 sha256=115f2de0f912d70ee9eed25c26b0460f4fe24213359dd46a0ffec3e96e24c911
Stored in directory: c:\users\dmitr\appdata\local\pip\cache\wheels\a6\b2\fb\eff238e22a7ceffee8c7a366ce7ff4011af13c77a103f870d4
Successfully built frida-tools
Installing collected packages: wcwidth, websockets, pygments, prompt-toolkit, frida, frida-tools
━━━━━━━━━━━━━╺━━━━━━━━━━━━━━━━━━━━━━━━━━ 2/6 [pygments] WARNING: The script pygmentize.exe is installed in 'C:\dev\tools\Python313\Scripts' which is not on PATH.
Consider adding this directory to PATH or, if you prefer to suppress this warning, use --no-warn-script-location.
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━╺━━━━━━ 5/6 [frida-tools] WARNING: The scripts frida-apk.exe, frida-compile.exe, frida-create.exe, frida-discover.exe, frida-itrace.exe, frida-join.exe, frida-kill.exe, frida-ls-devices.exe, frida-ls.exe, frida-pm.exe, frida-ps.exe, frida-pull.exe, frida-push.exe, frida-rm.exe, frida-trace.exe and frida.exe are installed in 'C:\dev\tools\Python313\Scripts' which is not on PATH.
Consider adding this directory to PATH or, if you prefer to suppress this warning, use --no-warn-script-location.
Successfully installed frida-17.2.17 frida-tools-14.4.5 prompt-toolkit-3.0.52 pygments-2.19.2 wcwidth-0.2.13 websockets-13.1
Printing a package property in CMake
By example of spdlog package:
find_package(spdlog 1.13.0 EXACT REQUIRED)
message("spdlog_FOUND: ${spdlog_FOUND}")
get_property(SPDLOG_INTERFACE_INCLUDE_DIRECTORIES TARGET spdlog::spdlog_header_only PROPERTY INTERFACE_INCLUDE_DIRECTORIES)
message(STATUS "Location of spdlog: ${SPDLOG_INTERFACE_INCLUDE_DIRECTORIES}")
Subscribing to all ByBit trade streams in Python
from pybit.unified_trading import WebSocket
from pybit.unified_trading import HTTP
from time import sleep
session = HTTP(testnet=False)
info = session.get_instruments_info(category="spot")
symbol_infos = info["result"]["list"]
websockets = []
def handle_message(message):
print(message)
def subscribe(websockets, symbols):
print(f'Subscribing to {symbols}')
ws = WebSocket(
testnet=False,
channel_type="spot",
)
ws.trade_stream(symbol=symbols, callback=handle_message)
websockets += [ws]
