C++ eda - Eda tool palatte components, layout, how they are coded with C++

Hi Friends,

I want to know, how c++ is used to design eda tools. I want to say that, I have seen that there are pallet components in eda tools and the layout and the schematic, how these things are designed with the help of c++. Please let me know. Thank you in Advance.

Regards,
Ajay