Blog: Articles on C++11 and Computational Finance (by Daniel J. Duffy)

Re. Wa. · 7/20/22

Alright, I found the detailed syllabus by clicking on something which at first just looked like graphics and not a button.

APalley · 7/20/22

Re. Wa. said:
Alright, I found the detailed syllabus by clicking on something which at first just looked like graphics and not a button.

@Andy Nguyen , anything we can improve there?

Daniel Duffy · 7/20/22

yes pleeze!
@APalley
@Andy Nguyen

Daniel Duffy · 7/20/22

For me videos are not an efficient way of studying/learning (there probably a few are exceptions, i.e.

How will you learn C++ otherwise? random internet copy and paste?

My videos are in 1:1 correspondence with code reality. Study them and then start coding. Be patient.

Get it working
then
Get it right
then and only then
Get it optimised

Daniel Duffy · 7/20/22

Daniel Duffy said:
yes pleeze!
@APalley
@Andy Nguyen

One way is to describe a course at two levels.

Online Courses :: Datasim

www.datasim.nl

@APalley
@Andy Nguyen

Andy Nguyen · 7/25/22

Re. Wa. said:
Alright, I found the detailed syllabus by clicking on something which at first just looked like graphics and not a button.

Hi,
I have updated the pages for the C++ courses changing the text link for the syllabus to say "Course Details". You can click on that link or button above it to get the syllabus PDF. I hope it's easier to find now.

Daniel Duffy · 7/26/22

UML class diagrams for Gang of Four (GOF) Design patterns.

Handy card.

Re. Wa. · 7/28/22

What are the reasons for the popularity of the C++ language in quantitative finance?
I have asked two "big shots" within the quantitative finance realm about which programming language to learn, they both mentioned C++.

Daniel Duffy · 7/28/22

Re. Wa. said:
What are the reasons for the popularity of the C++ language in quantitative finance?
I have asked two "big shots" within the quantitative finance realm about which programming language to learn, they both mentioned C++.

Did they give reasons or was it just "mentioned"?
And now you're asking me?

Re. Wa. · 7/28/22

To be honest, I did not dare to send a following email with further questions after receiving replies to the first one I sent.
The reason is that they replied late at night, which means (I guess) that they are very busy.

Daniel Duffy · 7/28/22

Re. Wa. said:
To be honest, I did not dare to send a following email with further questions after receiving replies to the first one I sent.
The reason is that they replied late at night, which means (I guess) that they are very busy.

Worlk work, work.
People should relax more, like doing C++.

Daniel Duffy · 8/12/22

FLOW CHARTS
are useful techniques to sketch the design of a program before coding in C and C++

Flowchart - Wikipedia

en.wikipedia.org

Re. Wa. · 8/12/22

Daniel Duffy said:
FLOW CHARTS
are useful techniques to sketch the design of a program before coding in C and C++

Flowchart - Wikipedia

en.wikipedia.org

I use flow charts for something else than a design sketch.
Could you give an example of how one could use it as you suggest?

Daniel Duffy · 8/12/22

Flow charts are very generic and have many specialisations. All kinds of enginers and busines analysts use it in one form or another.

DFD are cool and useful and Missing In Action as we see a process of widespread deskilling in software expertise during recent years. Software development savvy is ad-hoc etc. (copy-and-paste) a lot. Big anti-pattern.

What is Data Flow Diagram?

Quickly learn Data Flow Diagram (DFD). This DFD guide contains everything you need to know about DFD. Easily understand core DFD symbol with FREE DFD examples and more.

www.visual-paradigm.com

Every little helps.

Daniel Duffy · 8/12/22

Daniel Duffy · 10/17/22

21st century C++: Design Pattterns, C++20 Concepts and multimethods

This code contains:

1. Visitor pattern based on C++20 Concepts (provide-requires contracts).
2. Multimethods (the Holy Grail) .. what C++ tried for 30 years.
3. Multimethods with variadic parameters, a) object with multiple visitors,
b) a visitor with multiple objects.

Daniel Duffy · 10/17/22

C++:

// DJD 2022-10-9 version 0.9 #6

// (C) Datasim Education BV 2022



/*

A really modern implementation of a generic Visitor pattern that is an improvement on other approaches in C++:



        1. std::visit() and std::variant()

        2. Traditional Acyclic Visitor using subtype polymorphism, dynamic casting and

        possibly multiple inheritance.



The proposed solution is more maintainable than solutions 1 and 2 while at the same time having better performance and reliability properties than solution 2. Our solution uses a combination of

template methods and C++ Concepts.



We take the well-known example of 2d shapes (Point, Line, Circle) that can be visited in different ways.

The two visitors represent new functionality for drawing and scaling these shapes.



We note that we do not have a class hierarchy nor virtual functions. All behaviour is compile-time driven as it were.



C++ Concepts is a game changer.



This code contains:



        1. Visitor pattern based on C++20 Concepts (provide-requires contracts).

        2. Multimethods (the Holy Grail) .. what C++ tried for 30 years.

        3. Multimethods with variadic parameters, a) object with multiple visitors,

        b) a visitor with multiple objects.



        WE GIVE A STRIPPED DOWN VERSION TO FIT ON PAGE

        More later.

*/



#include <iostream>



// Visitor with templates,V2

struct Point;



// Using C++20 Concepts to define contracts/protocols

// 1. The baseline contract between GOF Context and Visitor

template <typename Visitor, typename Context>

    concept IVisitor = requires (Visitor & v, Context & c)

{

    v.visit(c);

};



template <typename Visitor, typename Context>

    concept IAccept = requires (Visitor & v, Context & c)

 {

        c.accept(v);

 };

 

 template <typename Visitor, typename Context>

    concept IAcceptVisitor = IVisitor<Visitor, Context> && IAccept<Visitor, Context>;



// Specialisations of Concept interfaces (from 2 to 1 template parameter)

template <typename Visitor>

    concept IPointVisitor = IVisitor<Visitor, Point>;





/* End of Protocol definitions*/





struct Point

{

    double x;

    double y;



    Point() : x(0.0), y(0.0) {}

    Point(double X, double Y) : x(X), y(Y) {}



    template <typename T> requires IPointVisitor<T>

        void accept(T& t)

    {

        t.visit(*this);

    }

};





// Specific visitors (Draw and Scale)

struct Draw

{

    void visit(Point& p)

    {

        std::cout << "("<< p.x << ", " << p.y << ")\n";

    }

 

 

};





struct Scale

{

    double fac;

    Scale(double factor) : fac(factor) {}

    void visit(Point& p)

    {

        p.x *= fac;

        p.y *= fac;

    }

 

};



// Multimethods, the Holy Grail of C++

template <typename Visitor, typename Context>

    void multimethod(Visitor& v, Context& c) requires IAcceptVisitor<Visitor, Context>

{

        v.visit(c);

        c.accept(v);

}





// Command multipattern ... a list of objects on a single visitor

 template <typename T, typename Visitor>

    void command(Visitor v, T& c)

 {

       c.accept(v);

 }





template <typename T, typename Visitor, typename ... Types>

    void command(Visitor v , T& arg, Types& ... args)

{ // 1 visitor, multiple contexts



        command(v, arg);

        command(v, args...);

}



 // Command multipattern ... a list of visitors  on a single object

 template <typename T, typename Visitor>

    void command2(T& c, Visitor v)

  {

      //  c.accept(v);

        v.visit(c);

  }



template <typename T, typename Visitor, typename ... Types>

    void command2(T& arg, Visitor& v, Types& ... args)

{ // 1 context, multiple visitors



        command2(arg, v);

        command2(arg, args...);

 }





int main()

{

 

    // Contract with C++ 20 Concepts

    {

        std::cout << "Contracts, points and lines\n";

        Point p1(2.0, -3.0);

        Draw draw;

        Scale mod(0.5);



        p1.accept(mod);

        p1.accept(draw);

        mod.visit(p1);

        draw.visit(p1);

        p1.accept(mod);

        draw.visit(p1);

    }



 

    {

        // multimethods

        std::cout << "Multimethod\n";

        Point p(2.0, 4.0); Point p2(20.0, 41.0);

        Point p3(-2.0, -4.0); Point p4(21.0, 42.0);

        Draw draw;

        Scale mod(0.5);



        // Magic

        multimethod(draw, p);

        multimethod(mod, p);

        multimethod(draw, p);



        std::cout << "variadics\n";

        command(draw, p);

        // Multimethods with variadic parameters

        command(draw, p, p2, p3, p4);



        // Object with multiple visitors

        command2(p, draw, mod, draw, mod, draw, mod, draw);

        command2(p2, draw, mod, draw);

    }

 }

Devon Kaberna · 10/18/22

Daniel Duffy said:

C++:

// DJD 2022-10-9 version 0.9 #6

// (C) Datasim Education BV 2022



/*

A really modern implementation of a generic Visitor pattern that is an improvement on other approaches in C++:



        1. std::visit() and std::variant()

        2. Traditional Acyclic Visitor using subtype polymorphism, dynamic casting and

        possibly multiple inheritance.



The proposed solution is more maintainable than solutions 1 and 2 while at the same time having better performance and reliability properties than solution 2. Our solution uses a combination of

template methods and C++ Concepts.



We take the well-known example of 2d shapes (Point, Line, Circle) that can be visited in different ways.

The two visitors represent new functionality for drawing and scaling these shapes.



We note that we do not have a class hierarchy nor virtual functions. All behaviour is compile-time driven as it were.



C++ Concepts is a game changer.



This code contains:



        1. Visitor pattern based on C++20 Concepts (provide-requires contracts).

        2. Multimethods (the Holy Grail) .. what C++ tried for 30 years.

        3. Multimethods with variadic parameters, a) object with multiple visitors,

        b) a visitor with multiple objects.



        WE GIVE A STRIPPED DOWN VERSION TO FIT ON PAGE

        More later.

*/



#include <iostream>



// Visitor with templates,V2

struct Point;



// Using C++20 Concepts to define contracts/protocols

// 1. The baseline contract between GOF Context and Visitor

template <typename Visitor, typename Context>

    concept IVisitor = requires (Visitor & v, Context & c)

{

    v.visit(c);

};



template <typename Visitor, typename Context>

    concept IAccept = requires (Visitor & v, Context & c)

 {

        c.accept(v);

 };

 

 template <typename Visitor, typename Context>

    concept IAcceptVisitor = IVisitor<Visitor, Context> && IAccept<Visitor, Context>;



// Specialisations of Concept interfaces (from 2 to 1 template parameter)

template <typename Visitor>

    concept IPointVisitor = IVisitor<Visitor, Point>;





/* End of Protocol definitions*/





struct Point

{

    double x;

    double y;



    Point() : x(0.0), y(0.0) {}

    Point(double X, double Y) : x(X), y(Y) {}



    template <typename T> requires IPointVisitor<T>

        void accept(T& t)

    {

        t.visit(*this);

    }

};





// Specific visitors (Draw and Scale)

struct Draw

{

    void visit(Point& p)

    {

        std::cout << "("<< p.x << ", " << p.y << ")\n";

    }

 

 

};





struct Scale

{

    double fac;

    Scale(double factor) : fac(factor) {}

    void visit(Point& p)

    {

        p.x *= fac;

        p.y *= fac;

    }

 

};



// Multimethods, the Holy Grail of C++

template <typename Visitor, typename Context>

    void multimethod(Visitor& v, Context& c) requires IAcceptVisitor<Visitor, Context>

{

        v.visit(c);

        c.accept(v);

}





// Command multipattern ... a list of objects on a single visitor

 template <typename T, typename Visitor>

    void command(Visitor v, T& c)

 {

       c.accept(v);

 }





template <typename T, typename Visitor, typename ... Types>

    void command(Visitor v , T& arg, Types& ... args)

{ // 1 visitor, multiple contexts



        command(v, arg);

        command(v, args...);

}



 // Command multipattern ... a list of visitors  on a single object

 template <typename T, typename Visitor>

    void command2(T& c, Visitor v)

  {

      //  c.accept(v);

        v.visit(c);

  }



template <typename T, typename Visitor, typename ... Types>

    void command2(T& arg, Visitor& v, Types& ... args)

{ // 1 context, multiple visitors



        command2(arg, v);

        command2(arg, args...);

 }





int main()

{

 

    // Contract with C++ 20 Concepts

    {

        std::cout << "Contracts, points and lines\n";

        Point p1(2.0, -3.0);

        Draw draw;

        Scale mod(0.5);



        p1.accept(mod);

        p1.accept(draw);

        mod.visit(p1);

        draw.visit(p1);

        p1.accept(mod);

        draw.visit(p1);

    }



 

    {

        // multimethods

        std::cout << "Multimethod\n";

        Point p(2.0, 4.0); Point p2(20.0, 41.0);

        Point p3(-2.0, -4.0); Point p4(21.0, 42.0);

        Draw draw;

        Scale mod(0.5);



        // Magic

        multimethod(draw, p);

        multimethod(mod, p);

        multimethod(draw, p);



        std::cout << "variadics\n";

        command(draw, p);

        // Multimethods with variadic parameters

        command(draw, p, p2, p3, p4);



        // Object with multiple visitors

        command2(p, draw, mod, draw, mod, draw, mod, draw);

        command2(p2, draw, mod, draw);

    }

 }

This is really good stuff - thank you for sharing.

Daniel Duffy · 10/18/22

Devon Kaberna said:
This is really good stuff - thank you for sharing.

Hi Devon,
Yes, Visitor 21st century and multimethods.
And there's more ... I am resuccitating the GOF Pattern intp C++20 style.
I'll keep posting here.

C++20 Concepts really tax my brain. Why? 7 plus or minus 2.

The Magical Number Seven, Plus or Minus Two - Wikipedia

en.wikipedia.org

Devon Kaberna · 10/18/22

Daniel Duffy said:
Hi Devon,
And there's more ... I am resuccitating the GOF Pattern intp C++20 style.
I'll keep posting here.

C++20 Concepts really tax my brain. Why? 7 plus or minus 2.

The Magical Number Seven, Plus or Minus Two - Wikipedia

en.wikipedia.org

The GOF pattern is long overdue to be revamped, so I'm really excited to learn more on your research and thoughts.

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