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Here are a few question-based titles that capture the essence of your article: * **How Can I Dynamically Load an Exported C Class?** (This directly addresses the core question of the content) * **

Barbara Streisand
Barbara StreisandOriginal
2024-10-25 17:28:31373browse

Here are a few  question-based titles that capture the essence of your article:

* **How Can I Dynamically Load an Exported C   Class?** (This directly addresses the core question of the content)
* **Dynamic vs. Static: What are the Best Methods for Expor

Dynamically Loading an Exported C Class

While exporting functions from a DLL is straightforward using __declspec(dllexport), handling class exports can be more complex.

Dynamic Loading using LoadLibrary()

Dynamically loading a class at runtime is not directly supported. Instead, consider using one of the following options:

  • Factory Function: Create objects using a specialized factory function that dynamically hooks them to their DLL offsets.
  • Delay-load DLL: Employ a delay-load DLL that is loaded after program initiation.

Compile-Time Linking Using Header and Library

For compile-time linking, use the following approach:

  1. Declare the class in the exported header file (e.g., class_decl.h).
  2. Export the class symbol using preprocessor macros (e.g., EXPORT_CLASS).
  3. Create an import library for dynamic linking (e.g., class_decl.lib).
  4. Link the application executable with the import library.

Preprocessor Technique for Exporting Class Symbol

<code class="cpp">#ifdef _WIN32
#ifdef CLASS\_DECL\_EXPORT
#define EXPORT\_CLASS __declspec(dllexport)
#else
#define EXPORT\_CLASS __declspec(dllimport)
#endif
#else
#define EXPORT\_CLASS
#endif

class EXPORT\_CLASS MyClass {
  // ...
};</code>

Additional Considerations

  • Implicit linking (using the preprocessor technique) provides a simpler and more reliable solution compared to late-binding using LoadLibrary().
  • If dynamic loading of a class is essential, consider using the factory function or delay-load DLL approach.

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