This project implements the plugin architecture in the C++ programming language. The plugin architecture usage is demonstrated through a simple calculator engine, which can be expanded with additional operations as plugins. The engine source code is originally shipped with two plugins: one for the addition operation, and another one for the subtraction operation.

The project build has been tested in Ubuntu 16.04 LTS.

From a terminal, navigate to the project root directory and type:

mkdir build && cd build
cmake ..
make

The following directories and contents should be created upon successful build:

~/Desktop/calculator_engine/lib/libapi.so
~/Desktop/calculator_engine/lib/libengine.so
~/Desktop/calculator_engine/plugins/libaddition_plugin.so
~/Desktop/calculator_engine/plugins/libsubtraction_plugin.so

While in build directory, type:

./calculator

The following is an example of the input and output of the calculator application:

Attempting to open lib libsubtraction_plugin.so ...
Added plugin (type=operation, name=sub)
Attempting to open lib libaddition_plugin.so ...
Added plugin (type=operation, name=add)
Calculator engine started
Enter operation: add
operandA: 1
operandB: 2
Loading library libaddition_plugin.so
Result: 3
Enter operation: mul
Operation not supported
Enter operation: sub
operandA: 4
operandB: 3
Loading library libsubtraction_plugin.so
Result: 1
Enter operation: exit
Calculator engine stopped
Clearing plugin registry

For example, to create a plugin for the multiplication operation:

1. Create a plugin_multiplication directory under src
2. Create CMakeLists.txt, multiplication_plugin.h and multiplication_plugin.cpp under plugin_multiplication
3. Implement those files in a similar way as e.g. the contents of plugin_addition folder
4. Open top-level src/CMakeLists.txt and add:

add_subdirectory("src/plugin_multiplication")

5. Re-build the project
6. The plugin should be now available to the calculator engine