Quiz Engine IV

Review — Quiz Engine III 5 min

• players and scores were two lists in step; turn was the row playing.
• mod wrapped the turn back to 1 after the last player.
• A question timer was the timer now, take away the timer when it was asked.
• The winner was found in two passes, so a tie could not hide.

Quick-fire

In Tile Maker, how did a whole level get from one project to another?

Today’s Topic 3 min

• A top five in two lists, kept in order with insert (thing) at (place) of [list v]
• A table the green flag never clears
• A question pack as one code, cut apart by split with a second input
• A front door — and a cold test with a real player

Learning outcome

By the end of this lesson you will be able to:

1. Keep a list sorted by inserting each new item in its place.
2. Pack a whole list into one piece of text, and unpack it.
3. Finish a game so a stranger can pick it up and play.

Learnt — a quiz that lasts 28 min

1 · Insert in order

Card Battle sorted a whole list with bubble sort. A top five never needs that, because it is already in order. A new score just needs its place: walk down the table until it beats the score there, and insert it.

define add to top five (name) (points)
set [place v] to (1)
repeat until <<(place) > (length of [top scores v])> or <(points) > (item (place) of [top scores v])>>
  change [place v] by (1)
end
insert (name) at (place) of [top names v]
insert (points) at (place) of [top scores v]
if <(length of [top scores v]) > (5)> then
  delete (6) of [top names v]
  delete (6) of [top scores v]
end
            

2 · The table survives the green flag

Look at what the green flag does not do: it never deletes the top lists. Each new game sets score to 0 but leaves the table alone — the same trick as Kart Racer’s best lap.

The table lasts as long as the project is open, and is saved with it. Reload the page and it goes back to whatever the project was saved with.

3 · A question pack in one code

A bank is a list of lines. Join them with ~ between, and the whole bank is one piece of text — a pack you can copy, send to a friend and paste in.

To load a pack, cut it at every ~. That is exactly what split does — except it always cuts at |. Give it a second input, cut, that says where to cut.

define split (text) (cut)
delete all of [parts v]
set [word v] to []
set [i v] to (1)
repeat (length of (text))
  set [letter v] to (letter (i) of (text))
  if <(letter) = (cut)> then
    add (word) to [parts v]
    set [word v] to []
  else
    set [word v] to (join (word) (letter))
  end
  change [i v] by (1)
end
add (word) to [parts v]
            

split (code) [~] :: custom
delete all of [bank v]
set [k v] to (1)
repeat (length of [parts v])
  add (item (k) of [parts v]) to [bank v]
  change [k v] by (1)
end
            

4 · A front door

A stranger opening your project needs to know what it is and how to start. A title, a how-to-play card and a Play button, all hidden when the game begins.

5 · The cold test

Give your quiz to someone who has never seen it. Say nothing. Watch, and write down every moment they hesitate or ask you something. Each one is a job for you: a clearer card, a better message, a guard on what they type.

Basic — the finished quiz 25 min

Open your quiz. This is where it all comes together.

Step 1 — the top five

1. Make the lists top names and top scores, and the variable place. Type three made-up names and scores in to start the table.
2. Make the add to top five My Block from Learnt section 1.
3. After the quiz loop: if the table has fewer than 5 rows or the score beats row 5, ask for a name and add it.

if <<(length of [top scores v]) < (5)> or <(score) > (item (5) of [top scores v])>> then
  ask (join [You scored ] (join (score) [ - that's in the top five! Your name?])) and wait
  add to top five (answer) (score) :: custom
else
  say (join [You scored ] (join (score) [. Not quite the top five - try again!]))
end
            

Step 2 — the front door

1. Save our title.svg and play.svg, and upload them as two sprites.
2. The Play sprite: when this sprite clicked, hide, broadcast (play v).
3. Move the quiz from under the green flag to when I receive [play v]. The title hides when it receives play too.

Read the table out

List monitors are fine for you; a player wants a proper table.

• Kiran says the whole table in one line: place, name, score.
• Hide the two list monitors.

set [line v] to []
set [k v] to (1)
repeat (length of [top scores v])
  set [line v] to (join (line) (join (k) (join [. ] (join (item (k) of [top names v]) (join [ ] (join (item (k) of [top scores v]) [   ]))))))
  change [k v] by (1)
end
say (line)
            

Your rank

Tell the player exactly where they came.

• After the insert, say “You came 2nd!” — or 1st, 3rd, 4th, 5th.
• The words come from a list, not from five if blocks.

add to top five [Jo] (8) :: custom
say (join [Jo, you came ] (join (item (place) of [places v]) [!]))
            

Refuse a bad pack

A friend’s pack might have a typo. Check it before it replaces your bank.

• After loading, cut every line at | and count its parts.
• If any line does not make 5, empty the bank and say which line was bad.
• This is Lesson 37’s bank checker, now with a second input.

set [bad v] to (0)
set [q v] to (1)
repeat (length of [bank v])
  split (item (q) of [bank v]) [|] :: custom
  if <<not <(length of [parts v]) = (5)>> and <(bad) = (0)>> then
    set [bad v] to (q)
    set [bad parts v] to (length of [parts v])
  end
  change [q v] by (1)
end
if <(bad) = (0)> then
  say (join [Pack loaded: ] (join (length of [bank v]) [ questions.]))
else
  delete all of [bank v]
  say (join [Bad pack: line ] (join (bad) (join [ has ] (join (bad parts) [ parts. Nothing loaded.]))))
end
            

A pack menu

One project, many quizzes.

• Keep three packs in a packs list, one code per row, and their names in pack names.
• Ask which pack to play, load it, and play it.
• Say the pack’s name with the score at the end.

Summary 5 min

• An ordered table stays ordered if every new item is inserted at its place.
• A score that beats goes above; one that only equals goes below.
• Anything the green flag does not reset survives every new game.
• A pack is lines joined with ~. split with a second input cuts it apart again.
• A finished game has a front door, and has been played cold by someone else.

Insert

Putting an item into a list at a place, pushing the rest down.

Pack

A whole question bank written as one piece of text.

Cold test

Watching someone play your game for the first time, without helping.

Hand in

Save your finished Quiz Engine, and write down three things from your cold test. Keep it — every quiz you make from now on can run on this engine.