moneycpp – a C++ library for handling monetary values

I have been working lately on a C++ library for handling monetary values, currencies, rounding and other related features. It is called moneycpp and it’s a C++ 17 header-only, cross-platform library available on GitHub.

The library is intended for being used in a variety of types of application including ERP systems, banking, finance, insurance, games, and others.

The following is a list of its core requirements:

JSON and XML to C# classes in Visual Studio

Although this feature is available for years in Visual Studio, I only recently discovered this gem that allows rapid generation of C# classes from either JSON or XML.

Here is how it works:

  1. Copy the JSON or XML code to the clipboard.
  2. In Visual Studio, go to Edit > Past Special and chose either Paste JSON as classes or Paste XML as classes.

Unit testing non-public types and members for .NET projects

Unit testing is usually used for testing public types and members. However, there are cases when you might need to test types or members that are not public. These could be internal classes or private helper methods, for instance. Whether that is proper unit testing or beyond its scope is not a discussion that I want to get into here. However, in this post, I will show how you can unit test non-public types and members from .NET assemblies.

When faced with the need for testing non-public types and members you can use several approaches:

  • change the accessibility to public; you can do that perhaps only for debug builds and keep the intended accessibility in release builds by using conditional compilation.
  • provide public members of a class that invoke private ones;
  • use reflection.

The first solutions involve changing the API only for the sake of the testing. The last solution avoids that but requires more work. To help with that, the Visual Studio unit testing framework provides some helper types that enable you to focus on the actual testing and be less concerned about the reflection details.

Troubles with Windows SDK

I recently installed a fresh copy of Visual Studio 2017 on a new machine and went on to build several projects some of them being VC++. The trouble was that I immediately run into a problem (actually the first problem was that MFC & ATL were missing because I forgot to check that in the list of Individual components so I had to install them separately). The problem was an error with a missing new.h header:

1>c:\program files (x86)\microsoft visual studio\2017\enterprise\vc\tools\msvc\14.15.26726\atlmfc\include\afx.h(62): fatal error C1083: Cannot open include file: 'new.h': No such file or directory

When a type is not a type

This article has been updated for C++20.

Let’s take a look at the following code sample:

template <typename T> 
struct foo
{
   foo(T) {}
};

int main()
{
   std::pair   p{ 1, "one" };
   std::vector v{ 1, 2 };
   foo         f{ 42 };
}

Here, p is a std::pair, v is a std::vector, and f is a foo. But there is no such thing as a std::vector type (nor std::pair or foo). std::vector<int> is a type, and std::vector<T> is a type template, but std::vector is just a placeholder that activates a C++17 feature called class template argument deduction (which we will call CTAD for short).

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croncpp – a C++ library for CRON expressions

A CRON expression is a string composed of six fields (in some implementation seven), separated by a whites space, representing a time schedule. CRON expressions are used in various job schedulers (such as the Linux job scheduler, the Quartz scheduler, Azure scheduler for functions, etc.). Recently, I have written a C++ library for parsing such expressions and determining the next occurrence of the scheduled time. The library is called croncpp. It is written in C++17, is header-only, open-source and cross-platform, and can be found on GitHub.