Struct Prose

pub struct Prose {
    pub text: String,
    pub url: String,
    pub lang: String,
    pub licence: String,
}

A piece of prose taken from somewhere, with what its licence obliges.

One value, not four fields. Wikipedia is CC BY-SA: the text may be reused, and attribution has to travel with it. A text field beside a separate optional url would make it possible — and therefore eventually certain — to hold the words without the credit: one code path that fills the first and forgets the second, one export that copies one and not the other, and the project is quietly out of compliance.

So they are the same value. There is no way to store the sentence without storing where it came from, in which language, and under what terms, because the type does not offer one.

Fields

text: String

The words themselves.

url: String

The page they came from, which is the attribution a reader can follow.

lang: String

Language code of that page, so a reader knows what they are getting.

licence: String

The licence, named as the source names it — CC BY-SA 4.0.

Stored per record, not looked up from a constant. It is the same string for every Wikipedia article today, so carrying a copy on each row looks like waste — about twenty-four bytes, ten kilobytes over a large library. It buys two things that a constant read at display time cannot.

It is a fact about the fetch, like SourceRecord::fetched_at: it says what these words were taken under, not what the current build believes they would be taken under now. Wikimedia has already moved once — CC BY-SA 3.0 to 4.0 — and with a constant that upgrade silently relabels every paragraph fetched before it.

And Prose is not Wikipedia’s. It is prose with its terms, so the next source of a biography — a plugin, a label, a discography site under quite different terms — files it in this same field, and the record says which. Moving the licence out to the source that usually supplies it would make the second source a special case of the first.

Implementations

impl Prose

pub fn credit(&self) -> String

The line that has to appear wherever the text does.

The language is named, and that is not decoration. This text is fetched in one language and kept in one language, so a reader who wanted French and is reading English has no way to tell whether their preference was ignored, whether the article does not exist in French, or whether the prose was fetched before they expressed a preference at all. The field was stored from the first version and displayed nowhere — the same dead end source_id and the fingerprints had. Now the screen says which language it is, and the way to ask for another is one line below.

Trait Implementations

impl Clone for Prose

fn clone(&self) -> Prose

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Prose

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl PartialEq for Prose

fn eq(&self, other: &Prose) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Eq for Prose

impl StructuralPartialEq for Prose