Fran from Illinois shared a great debug story from a previous job. Similar to The Dog Barks When the Phone Rings story, this took place at a phone company repair office. The phone company received a call for help after a new phone installation. The complaint was that after the phone installer left the house, the owner could no longer close their door.
Okay, phones have absolutely nothing to do with doors. Everybody knows that.
“I’m sorry, I don’t understand. Why do you think that the phone installation could possibly have anything to do with your door?”
“Because the door was fine before they installed the new phone jack, and now the door cannot be closed,” the customer replied firmly.
“Well, I am sorry, I am struggling to understand how the two things could be connected. Are you saying that maybe they left a cardboard box or something that is keeping the door from closing? Perhaps some piece of debris is wedged into the hinge-side of the door? Does this door open into or out of the room?”
“No, no, it is nothing like that. This door does not have hinges.”
“Um, excuse me? What kind of door does not have hinges?”
(Wait for it…)
“A pocket door,” replied the customer.
Now some of you have already figured out where this story is going and are already laughing as you realize what has happened in this story and what mistake the installers made. But don’t worry if you have not quite leapt to final understanding.
A pocket door is often used between two interior rooms such as leading into a kitchen. The door itself moves on rollers and slides into a special slot or empty space within the wall called a “pocket.” (Many folks will recognize the sliding doors from the original Star Trek series as pocket doors.)
What had clearly happened in this case was that the telephone installer had not recognized the presence of the pocket door and had drilled through the wall and door and then threaded the phone wire through the hole in the wall and door. This wire then acted as an anchor, holding the pocket door in place. No easy pulling was going to move that door, unless all of the conductors and insulator sheathing could have been snapped (which coincidentally would have broken the newly installed phone service).
How many times have you designed yourself into a corner because you did not see a hidden constraint like the presence of this pocket door? How much time and effort is added to a project when you have to back-track and not only solve the problem correctly (allowing for all of the constraints) but also have to undo and fix the problems created by the first incorrect solution?
I know that you would never make this mistake. You would make sure that you were aware of all of the structure around your problem and solution before moving forward to implement your solution. Unfortunately, I can easily envision myself making this mistake. And perhaps, that is why it makes me laugh (and cry) so much.