How can a Plugin call Other Plugins with C++? - c++

Question

This is a plugin system which is based on the factory pattern.
Each plugin extends the Plugin class and implements a factory that returns the extended class to the kernel.
Plugins are compiled as shared libraries. Kernel checks the plugins/ directory and loads all libraries at runtime.
When the red button is clicked, the kernel calls call_on_red_click() on every loaded plugin.
// Plugin.h
class Plugin {
public:
virtual void call_on_blue_click() = 0;
virtual void call_on_red_click() = 0;
}
// MyPlugin.h
class MyPlugin : public Plugin {
public:
void call_on_blue_click() {/*[...]*/}
void call_on_red_click() {
// Does something
// Optionaly, activate teleporter
}
}
Plugin *plug_factory() { return new MyPlugin; }
// MyOtherPlugin.h
class MyOtherPlugin : public Plugin {
public:
void call_on_blue_click() {/*[...]*/}
void call_on_red_click() {
// Does something else
// Optionaly, activate teleporter
}
}
Plugin *plug_factory() { return new MyOtherPlugin; }
The teleporter is compiled separately and may not be present in every installation (It's shiped by itself).
Lets say that MyPlugin and MyOtherPlugin want to activate the teleporter if it is present.
Questions:
Should the Teleporter be a kernel Plugin or something else?
Is there a design pattern for this?

Answer 1

Sounds like you want the decorator pattern
Which will allow you to have a class that loads the dll, and then your plugins can then query your decorator if teleportation is enabled. You can then disable it for any reason, not just because the dll isn't there; or enable it even if the dll isn't there but implemented in another way.