SIGINT handler in cxx

#include <iostream>
#include <csignal>
#ifdef _WIN32
#include <Windows.h>
#else
#include <unistd.h>
#endif


using namespace std;

void signalHandler( int signum ) {
    cout << "Interrupt signal (" << signum << ") received.\n";

    // cleanup and close up stuff here
    // terminate program

    exit(signum);
}

int main () {
    // register signal SIGINT and signal handler
    signal(SIGINT, signalHandler);

    while(1) {
        cout << "Going to sleep...." << endl;
        sleep(1);
    }

    return 0;
}

Convert python dictionary to object

Consider having json response from REST service stored internally in dictionary object. Now, following code converts content of the dictionary to instace of class Test.

Keep in mind though it's just simple demonstration. Enhancement in form of data validation might be required!

from collections import namedtuple

class Test:
    def __init__(self, name : str, description : str, float_number : float): 
        self.name, self.descrition, self.float_number  = name, description, float_number

    def __repr__(self) -> str:
        return f"Test class data: name='{self.name}', description='{self.descrition}', number={self.float_number}"

paramDict = dict(name="Name Property Value", description="Description Property Value", float_number=102.0036)

tstInstance = Test(*(namedtuple('x', paramDict.keys())(*paramDict.values())))

print(repr(tstInstance))

Running the code above prints following representation of the object on the std output:

Test class data: name='Name Property Value', description='Description Property Value', number=102.0036

Create trustore and keystore for local Kafka and Zookeeper on Windows

Scenario:

1. Needed to use local Zookeeper and Kafka with existing CA certificate as well as existing consumer certificate. 
2. Hence needed to be able to use specific CN for 127.0.0.1, not a localhost
3. Modification of windows hosts file not allowed

All samples I found on the net presumed that CA needs to be generated. My use case was different. I was given with CA and client certificate and I needed to use defined certificate chain for authentication.

Used Git Bash i.e. cygwin for this exercise, hence winpty presence on line with openssl command.

 keytool -genkeypair -keyalg RSA -keysize 2048 -alias projenvlocal -dname "CN=projenvlocal" 
    -ext SAN=DNS:projenvlocal,DNS:localhost,IP:127.0.0.1 -validity 3650 -keystore server.keystore.jks 
    -storepass pwd1234 -keypass pwd1234 -deststoretype pkcs12  

 keytool -keystore server.truststore.jks -alias CARoot -import -file projEnvCALocal.crt 
    -storepass pwd1234 -noprompt

 keytool -keystore server.keystore.jks -alias projenvlocal -certreq -file localhost.csr 
    -storepass pwd1234  

 winpty openssl x509 -req -CA projEnvCALocal.crt -CAkey projEnvCALocal.key -in localhost.csr 
    -out localhost-signed.crt -days 3650 -CAcreateserial -extfile sign-cert.cnf 
    -extensions server_cert -passin pass:keypwd  

 keytool -keystore server.keystore.jks -alias CARoot -import -file projEnvCALocal.crt 
    -storepass pwd1234 -noprompt  

 keytool -keystore server.keystore.jks -alias projenvlocal -import -file localhost-signed.crt 
    -storepass pwd1234  

* passwords are just illustrative of full command line

This part below is the main thing for being able to use certificate's CN as user name for Kafka authentication on localhost/127.0.0.1

   -dname "CN=projenvlocal" -ext SAN=DNS:projenvlocal,DNS:localhost,IP:127.0.0.1

Performing of script above create two files, server.trustore.jks and server.keystore.jks .These files need to be used in ssl section of Kafka's server.properties and Zookeeper's zoo.cfg (file names may differ though).

The Pylance - Goodbye Kite

Goodbye Kite.

Fast, feature-rich language support for Python in Visual Studio Code

The name Pylance serves as a nod to Monty Python’s Lancelot, who is the first knight to answer the bridge keeper’s questions in the Holy Grail.

(cheers John Cleese et al.)

Expecting Pybrian plugin in the near future :)

The Quntopian has drawn to the close

The Quantopian has been brought to the end but some of their valuable resources have been placed on the github.

[1] Quantopian research 

[2] Community classes 

[3] ... (?)

Black-Sholes delta

import numpy as np 
from scipy.stats import norm

def delta(flag, s, k, t, r, v): 
  d1 = (np.log(s/k)+(r+v*v/2)*t)/(v*np.sqrt(t)) 
  if flag == “C”:
    return norm.cdf(d1) 
  else: 
    return norm.cdf(-d1) # +signed put delta

Type = ‘C’ # call
S = 97.65 # underlying
K = 100.00 # strike
T = 30/365 # 30 days to expiry (in years)
R = 0.00 # “risk-free” rate
V = 0.12 # 12 vol
delta(Type, S, K, T, R, V)
0.25044822

Type = ‘P’
S = 3000
K = 2900
T = 30/365
R = 0.00
V = 0.20
delta(Type, S, K, T, R, V)

0.27

S = 2950
T = 29/365
delta(Type, S, K, T, R, V)

0.37

LNK2001: unresolved external symbol __imp__PyObject_IsTrue

Recently I was experiencing following liknking error [1] .
I was checking path VC++ directories settings, upgrading from boost 1.55 to 1.57, still the same issue. After couple of ours, the resolution was so simple, I could not believe I can be so absent minded.

Never try to compile project referencing 32bit of boost, and linking 64bit Python engine.

[1] error LNK2001: unresolved external symbol __imp__PyObject_IsTrue    %PATH%\libboost_python-vc120-mt-gd-1_55.lib(class.obj)   

Boost::Python callback triggered from Non-Python created threads

Consider  we have virtual/abstract C++ class that's fully implemented in Python. And for some sake of necessity we have a callback method (e.g. as some sort of event) that is being triggered from different thread on C++ side and is handled in Python .
In such case corresponding callback methods have to manage global interpreter lock state with PyGILState_STATE member variable.
So the resulting C++ callback class definition will look like below (notice that Python method calls are wrapped up with GIL state handling code).

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33

class SessionStatusListenerCallback : public SessionStatusListener { public: SessionStatusListenerCallback(PyObject *pyObject) : self(pyObject) {} SessionStatusListenerCallback(PyObject* pyObject, const SessionStatusListener& listener) : self(pyObject), SessionStatusListener(listener) {} void onSessionStatusChanged(O2GSessionStatus status) { // GIL state handler PyGILState_STATE gstate; gstate = PyGILState_Ensure(); // Python callback call_method<void>(self, "onSessionStatusChanged", status); // GIL handler release PyGILState_Release(gstate); } void onLoginFailed(const char* error) { // GIL state handler PyGILState_STATE gstate; gstate = PyGILState_Ensure(); // Python callback call_method<void>(self, "onLoginFailed", error); // GIL handler release PyGILState_Release(gstate); } private: PyObject* const self; };

Microsoft Visual C++ Compiler for Python 2.7

New tool Microsoft Visual C++ Compiler for Python 2.7 is available. 
I have not tested it yet. But solution for: 
The typical error message you will receive if you need this compiler package is Unable to find vcvarsall.bat. 
 sounds promising :)

Handling "AddressAccessDeniedException: HTTP could not register URL" error

Having self hosting WCF service one can get following exception:

AddressAccessDeniedException: HTTP could not register URL http://+:13025/

By default, listening at a particular HTTP address requires administrator privileges. Since application users does not often have such privileges it's necessary to allow port listening for particular user or group via nesth.

E.g.

netsh http add urlacl url=http://+:13025/applicationsvcs/booking user=DOMAIN\app_account