Hits follow the mail list

Lesson map

Lesson 11. Map, example, EX057.

flowchart TD
  M["Three mail rows, written order"] --> S["Membership in the valid set"]
  S --> H["Two tuples, mail order"]
  H --> Q{"Did the shared-list order win?"}
  Q -->|No| K["vol-07 then office"]

The set answers yes or no. The mail list chooses the sequence.

Logical drawing

mail order
  vol-07, donate-elmfield.example
  vol-12, news.example
  office, elmfield-giftaid.example
printed hits
  vol-07 then office
not a sort key
  the order of shared

Learning outcomes

After this chapter, you should be able to:

Read the hit list as mail order.
Say what the set is used for.
Refuse a hit line that starts with the office.

11.1 Membership does not reorder. The comprehension walks `mail`.

The hit line keeps a mail row when its domain or address is a member of the set of valid values. A set has no order, so it cannot be the sequence of the result. The comprehension walks mail from top to bottom. vol-07 is first and matches, vol-12 is second and does not match, and office is third and matches. The printed list is therefore vol-07, then office. news.example never becomes a tuple in that list.

shared listed the GREEN domain first and the AMBER domain later. That writing order is not the hit order, even though both names match. Swapping the hit tuples to follow shared would be a different list. The print uses Python's representation of a list of tuples, with single quotes and the parentheses. Those marks are the representation, not extra evidence.

Lesson table; scroll horizontally to read all columns →

Choice	Source
Which rows qualify	Set membership
Which qualified row prints first	Position in `mail`
Whether vol-12 appears	It does not qualify
Shared-list order	Not the hit sequence

11.2 Worked example

Lesson table; scroll horizontally to read all columns →

Offered order	Why it is or is not the print	Decision
vol-07 then office	Mail order, with the miss skipped	Keep
Both qualifying names present	Their rows matched	Keep
"Office first, because AMBER is more sensitive."	No severity sort	Refuse
"The hits follow the shared list."	The walk is `mail`	Refuse

Synthetic case. The hit list has two tuples.

Errors and limits

Do not let a label's seriousness reorder the mail walk.

Apply

EX057 — Hit order. The print lists vol-07 and then office. Does that order come from shared, and where is news.example?
Show marking criteria
Rubric: 3 = the order is the mail list; the set only tests membership; news.example is a mail row that does not qualify; do not sort by label;; 2 = mail order, and the third row is not a hit;; 1 = one tuple;; 0 = none.