How to Create and Use Dynamic Shared C Class Libraries on Linux?

Creating and Using Dynamic Shared C Class Libraries on Linux

Creating a Shared Class Library

To create a shared C class library, you can follow these steps:

1. Define the header file, .h, declaring the class and its member functions. Remember to use virtual member functions to enable dynamic linking.
2. Implement the class in a separate source file, .cc, including the header file.
3. Define external C functions for object creation (create_object) and destruction (destroy_object).
4. Use #include to incorporate the header file and using namespace std; to use the standard namespace.
5. Compile the library using g -fPIC -shared on Linux or g -dynamiclib -flat_namespace on Mac OS X, generating a shared object file (.so).

Using Shared Class Libraries

To use shared class libraries in a separate executable:

1. Include the necessary header files.
2. Load the shared library using dlopen.
3. Use dlsym to get function pointers for create_object and destroy_object.
4. Create an instance of the class using create_object.
5. Call member functions on the instance.
6. Destroy the instance using destroy_object.
7. Close the shared library using dlclose.

Additional Tips for Plugin Systems

For a plugin system, derive your classes from a base class and make all required functions virtual. Plugin authors can override the virtuals and implement the create_object and destroy_object functions. This way, your main application remains unchanged.

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