the EXPORT directive (or a similar mechanism) is an essential part of making functions accessible from a shared library (DLL) or dynamic link library, especially when those functions are intended to be used by external code, such as code written in another programming language like Python.
In C, when you declare a function with EXPORT or an equivalent directive, you are essentially telling the compiler that this function should be visible and accessible externally. The exact syntax may vary depending on the compiler and platform. For example, on Windows, __declspec(dllexport) is commonly used, while on Linux, you might use attributes like __attribute__((visibility("default"))).
Here's a summary of how it works:
c
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#ifdef _WIN32
#define EXPORT __declspec(dllexport)
#else
#define EXPORT __attribute__((visibility("default")))
#endif
EXPORT int add(int a, int b) {
return a + b;
}
In this example:
On Windows (_WIN32), EXPORT is defined as __declspec(dllexport), which is a Microsoft-specific directive.
On other platforms, EXPORT is defined as __attribute__((visibility("default"))), which is a common way to export symbols on platforms like Linux.
When you compile your C code into a shared library (DLL), the functions marked with EXPORT become part of the library's interface and can be accessed from external code.
In Python, when using ctypes to access functions from the shared library, the EXPORT or equivalent directive ensures that those functions are visible and callable from the Python code, allowing for seamless integration between C and Python.