outstanding bugs

outstanding bugs = known malfunction

outstanding here mean “known”

when to use private constructor

constructor must be declared as public if you want to use ‘new ClassName()’.

Sometimes, you want constructor to be private so it won’t be called outside of the class. That is when you are using singleton.



  1. Constructor Argument Promotion —- The class members will automatically be created and assigned to what is passed into the constructor.
  2. lambad function using ==>  e.g., $squared = array_map($x ==> $x*$x, array(1,2,3));
  1. make a choice from a range of possibilities.

hg graft

hg graft: apply a commit from another branch to current branch

hg rebase -d master: apply your current branch with master branch changes. If a file is in master, but not on your current brach. That means your current branch delete the file.