Category Archives: Design patterns

Separating constraints, iterations and data (C++11)

Two recent posts in Bartosz’s programming cafe describe nice application of list monad to solve the following puzzle:

send puzzleEach letter corresponds to single digit. There are a lot of methods to solve this. Bartosz is using list monad which is very simular to list comprehension methods which were described here. While this maybe not the fastest way to solve this specific puzzle, his approach shows the ways to solve large cluster of similar but smaller problems which we meet at basic “production” level. SEND+MORE problem may be is not so good example to show power of list monad because of one very important problem i want to discuss in this post.

Continue reading

Templates as first-class citizens in C++11

templates as citizens

C++11 treats functions as first-class citizens and this gives us ability to construct a lot of nice things as design patterns borrowed from functional languages. Meanwhile C++ has very powerful template metaprogramming. This post is aimed to make templated functions closer to first-class citizens, and to construct some simplicity and beauty which you can get from it.

Also here will be implementation for currying of such functions! If you don’t know what currying is – just remember std::bind.

And to make it shine we’ll add piping. (This article will improve some ideas from post about functional piping ). This step is optional and you can replace such piping with commas and function calls.

Continue reading

10 ways to not shoot yourself in the foot using C++11

Within C++, there is a much smaller and cleaner language struggling to get out (Stroustrup)

The following text could be modified – current rev.1.0

Very often i hear from java/erlang/etc people that C++ is so bad that it is very unwise to use so-old-school language now, when we have more ‘safe’ higher level languages. Everybody heard about foot-shooting using C++.  What about C++11?

Bjarne said that C++11 feels like whole new language and, at first, i did not take it seriously as modifications looked more as minor additions (especially for boost users). Now i changed my mind – using new features combined together can transform your way of coding into new form. I’m talking not about adding new features to your code, but about changing your coding style.

How not to shoot yourself in the foot? Here is the list of my rules to make the C++ coding life sweet and easy. This is simple convention to follow and can be adopted very fast. Not only it gives more stable implementation but also more clean and understandable design.

This convention is composition of Scott Meyers rules, Functional programming ideas and reducing-complexity ideology by Steve McConnell.

Continue reading

How to make simple CQRS implementation without Event Sourcing

Here I will try to describe the concept of CQRS without event sourcing based on some other principle instead. The concept to organise your data and messages to create scalable and reliable CQRS/Messaging-based architecture without additional complexity from event store.


At first here is small introduction on what SQRS is. I suppose you are familiar with MVC model and use it on daily basis. And i suppose you understand benefits of separation your code into separate modules.

CQRS – Command-Query Responsibility Segregation. CQRS just separates model into 2 separate parts – READS model and WRITES model. They also can be referenced as Query model and Command model.

Continue reading