In the realm of programming languages, C++ and Ada are both prominent choices. While C++ is known for its versatility and power, Ada is renowned for its safety and reliability. Ada compilers often provide extensions to support interoperability with C++ code. In this blog post, we will explore some of the popular Ada compiler-specific extensions that facilitate working with C++ in Ada.

1. Ada/C++ Interoperability

The Ada programming language provides specific features to enable seamless integration with C++. These extensions allow Ada programs to call C++ code directly.

GNAT Extensions

GNAT, the GNU Ada compiler, offers several extensions for C++ interoperability. These extensions include:

• Pragma Import: With pragma import, Ada can import individual C++ functions or entire C++ classes. This allows for easy integration between the two languages.
• Access Types: Ada’s access types provide a mechanism to create pointers to C++ objects and access them directly.

For example, to import a C++ class into Ada and use it, we can use the following syntax:

pragma Import(Cpp, MyClass);
type My_Ada_Class_Access is access all MyClass;

AdaCore Extensions

AdaCore, the primary provider of Ada language technologies, also offers compiler-specific extensions for Ada/C++ interoperability:

• Pragma COPY: This pragma allows Ada code to interface with C++ objects, enabling Ada programs to access and manipulate the underlying C++ data directly.
• Interface C++: The interface keyword can be used in Ada to define interfaces to C++ classes, allowing Ada code to call C++ member functions.

Here’s an example of using the interface keyword to access a C++ class in Ada:

with Ada.Cpp_Interfaces;

package My_Ada_Cpp_Interface is
   type My_Cpp_Class_Interface is interface;
   function Get_Instance return My_Cpp_Class_Interface;
end My_Ada_Cpp_Interface;

2. C++ Bindings for Ada Libraries

In addition to enabling Ada to interoperate with C++, Ada compilers also provide mechanisms to generate C++ bindings for Ada libraries. This allows developers to use Ada libraries in their C++ projects seamlessly. The process involves generating C++ header files from Ada library specifications.

GNAT, for instance, offers the gnatbind tool to generate C++ bindings for Ada libraries. The generated C++ header files can then be included in C++ projects, providing access to the Ada functionality.

Conclusion

Ada compiler-specific extensions make it possible to integrate C++ code into Ada programs and leverage Ada libraries in C++ projects. The GNAT and AdaCore extensions provide ways to seamlessly interoperate between the two languages while maintaining the benefits each language offers. By utilizing these extensions, developers can combine the power, versatility, safety, and reliability of C++ and Ada in their software projects.

#Ada #C++