Class constructor

Note: My advance apologies if this has been already asked

I would like to know when a class constructor is actually called?
Also, which component calls it (is it the factory)?

Thanks,

In reply to verif_learner:

The one and only way a class constructor gets called is with an explicit call to new(). The code inside the factories create() method calls new(). Please see my SystemVerilog OOP course where I detail the mechanism for the factory create method.