While debugging a problem with some C code, I came across this laugh-out-loud funny (in a very geeky way) explanation of one of the evils of the short-circuit evaluation of logical expressions.
Stick with it, it’s really quite funny.
Mom (thinks in VB-ish):
If kid.CleanTheDishes() And kid.DoHomework() Then
we.GoToMovie you.PickMovie()
End If
Child (thinks in C-ish)
if (me->CleanTheDishes() && me->DoHomework())
{ we->GoToMovie(me->PickMovie());
} else
{ me->fool_around();
}
boolean CleanTheDishes()
{ ...
if (kitchen->Inventory("soap") SoapNeeded())
{ shoppingList->add("soap");
todo->add("Clean The Dishes");
return false;
}
...
}
Mom:
If Todo.Contains("Clean The Dishes") Then
Ask kid, "why didn't you clean the dishes"
End If
Child:
mom->show(kitchen->Inventory);
mom->show(shoppingList);
Mom:
If kid.Explanation.IsSatisfactory() Then
Pat kid
End If
If Not kid.Homework.IsDone Then
Ask kid, "why didn't you do your homework"
End If
Child:
if (mom->makes_no_sense())
{ mom->explain("Because && short-circuits");
mom->explain("See, doing homework is just a side effect");
mom->explain("I already knew that !we->GoToMovie(...)");
}
Mom:
kid.GetSupper = False
kid.SendToRoom
Child:
while (me->in_room)
{ me->grumble("She just doesn't understand...");
}
I can see myself asking Nicholas whether he’s using .NET or C-style evaluation one day… (g)
Crossed Wires 