Using C# from native C++ with the help of C++/CLI (fixed and enhanced)

Important note

This article replaces the previous one with the same title.
Indeed the previous C++/CLI wrapper implementation had a flaw that created memory corruption.
This issue has been fixed in the following implementation.
Moreover I’ve used it as an opportunity to greatly enhance the content, especially the description of the C++/CLI wrapper implementation, design rationales being now included.

Update note

The article has been updated on the 19th of June 2016 to integrate 3 fixes:

  • the YahooAPIWrapper‘s destructor is correctly declared in the header file to avoid memory leaks,
  • the YahooAPIWrapper‘s definition/cpp file does not redefine the class and the __declspec(dllexport) metadata has been moved to the header file to avoid compilation errors,
  • the YahooAPIWrapper‘s and native C++ program’s implementations have been updated to take into account the new fields names of Yahoo API to avoid runtime exceptions.

Introduction

When it comes to software development in a professional environment, heterogeneity is the rule not the exception: you often need to interact with systems developed with other technologies.

I’ve been recently faced with such a situation: a team that uses only native C++ needed to retrieve data using the object-oriented API of another team that develops only in .Net with C#.
This is a relatively uncommon scenario (just look at the number of articles on the subject), the standard case being new systems based on the .Net platform, developed in C# or VB.Net, needing to interact with legacy systems developed in native C++.

I’ve used the C++/CLI platform due to its unique ability to mix managed (.Net) and native code in one place and is then the ideal tool for building bridges between these two worlds using simple wrappers: the native face of the wrapper can be consumed by the legacy components and its managed face can directly use the C# API.

In this article I’ll illustrate how I’ve tackled the issue by building a simple C++/CLI wrapper, using a similar use-case: market-data retrieval from Yahoo.

Continue reading

Extend your VBA code with C#, VB.Net or C++/CLI

Introduction

If you have an important VBA code base you know how difficult it is to maintain it, not because VBA is inherently a bad or poor platform but because the developers are often either end-users not aware of good development practices or professional developers not skilled enough in VBA development who have learnt it on the job. In both cases, more often than not, you end up with poor quality source code.

There is other forces that make VBA development less appealing, as the pressure of software vendors like Microsoft who’d like to sell you not just Office but Office+Visual Studio and then promotes other technologies like .Net with languages such as C# and VB.Net. Just have a look at the evolution of the VBA editor design and capabilities since 10 years and you’ll understand that it does not benefit from fanatic development and promotion efforts.

It’s why you should avoid the headlong rush and restrict your VBA development efforts to the bare minimum: for new developments you should consider other languages and platforms like C# and VB.Net with the .Net framework as they seamlessly integrate with the Office suite, with little overhead compared to the direct integration of VBA, and give you access to a wealth of modern technologies.
But don’t be fooled by the FUD about the dangers of keeping a legacy VBA code base and do your due diligence: does the guy who suggest you a full migration will do it for free or is he paid for the job? ;) A full migration may be a necessity: not because the platform is VBA but because the application is buggy, undocumented, out of control and using it creates a true operational risk, and this is true for any application and technology including the newest.

Then, if you have a VBA application that is working perfectly, is documented and controlled, an alternative to both the headlong rush and the full migration is the integration of .Net components with VBA, you then use a future-proof technology to develop new features and/or replace legacy features as you go along, avoiding the big-bang effect.

So now you know what to do and right now I’ll show you how to do this seamless transition from VBA to greener pastures by implementing a simple API with three popular .Net languages: C# (the king), VB.Net (the prince) and C++/CLI (the Jack of all trades, master of none).

Continue reading