Glossary

The framework’s terms, each with its current name and a plain definition. When Phase 2 of the comprehensibility rework renames one, the old name is kept here as “was X” so a reader coming from older code or docs can find it.

  • page — what a handler returns: one or more frames sharing a page number.

  • frame — one screenful, 24 rows of 40 cells; a page too long for one has several, keyed a to z.

  • footer (the prompt row) — render_footer(items, FOOTER_WIDTH) composes it; FOOTER_WIDTH (was ROOM) is the cells it has. A FooterItem carries a Priority: ESSENTIAL/PRIMARY/SECONDARY, and ALIAS (was REDUNDANT) for a key already shown under another name. RowWriter.end_background() (was plain()) closes a coloured background so what follows sits on black.

  • attribute (was Control) — a teletext spacing attribute: a colour or character-set code that takes a cell of its own and shows as a blank. controls.Attribute; is_attribute_code (was is_control_code) tells one from a character. Not to be confused with encoding.ScreenControl, the C0 cursor and screen controls.

  • span (was Run) — a stretch of cells on one row sharing a background colour, as RowWriter lays a coloured band. canvas.Span. The composition layer keeps its own Run for a different job, which is why this one moved.

  • outsized letters — lettering.place draws a string in double or quadruple size; rows_needed (was rows_for) and cells_needed (was cells_for) say how many rows and cells it will take before it is drawn.

  • mosaic font — a bitmap face measured in blocks, drawn as lettering. The shipped faces are read by font.read_font from the framework’s own text format; yaff.read_yaff reads the YAFF format instead, so a face from a collection such as the hoard of bitfonts can be loaded without vendoring it.

  • part — a piece of a page’s body between the rules: a menu, some lines, a picture, a form. layout.Part. A part says which frames it appears on: OnOneFrame (was Once), OnEveryFrame (was Every), Flow (was Flowing, and what a bare drawable means), or FrameBreak (was Break).

  • sequence part (was Formatter/RowFormatter) — a part that lays out a homogeneous sequence of entries: a menu, a listing, a table of figures. Subclass formatting.SequencePart, or RowSequencePart for one whose entries are written left-to-right along their rows. Its gap (was separation) is the blank rows between entries, its choose_hint (was selecting_hint) the footer item shown when the entries can be chosen. Figures names its two columns’ widths label_width and figure_width (were label and figure).

  • entry — one item in a sequence a sequence part lays out, such as a line of a menu. formatting.Entry. Lines takes its lines as entries, passed first and without a keyword (was the said= keyword). PageLayout.item_noun (was item) is what the service calls one, so a heading can read “3 posts”.

  • Custom (was Drawn) — a part of a stated height a page draws itself, cell by cell: a picture, a grid, a masthead. layout.Custom(rows, draw).

  • place — what a custom part does: place(canvas, room) -> Placed, drawing as much as fits and saying what is left. Space (was Room) is what the frame has left; Placed (was Placement) carries the rows used, a Claim (was Offer) of the keys claimed, and a remainder (was rest). Two claims merge with Claim.merged_with (was Offer.and_then).

  • furniture — the fixed structure a page is drawn into, around its parts: a Header, Rules and a Footer (was Prompt). layout.Furnishing, DEFAULT_FURNITURE. A furnishing is told a FrameContext (was Summary); its edge is Edge.TOP/Edge.BOTTOM (was Edge.FOOT).

  • route — a pattern bound to a handler, carrying the page’s name and keywords. PageRoute. app.route(name) (was page_info) is the declared route by name, app.routes() (was pages()) all of them, and app.match(address) (was route(address)) what a page number matched.

  • router — collects the routes a module of handlers declares with @router.page, spread into a service as Sextile(pages=[*router, ...]). PageRouter (replaced the free @page decorator and routes_in). app.add_keyword (was alias) gives a page a second page number under a word; app.add_converter (was converter) teaches the patterns a new field type.

  • readership pages — the framework’s own history pages: Sextile.recent_page (was lately_read), popular_page (was most_read) and callers_page (was who_has_called), each built from the visit log.

  • pattern — the page-number template a route matches: literal digits and named fields, such as 82{post_id:int}.

  • address — a page number a reader is at, resolved from a pattern. PageAddress.

  • keyword — a word a reader keys in place of a number, *MAIN# for *1#; set by a route’s keywords=.

  • choices vs moves — choices are keys that lead somewhere, such as a menu’s digits; moves are keys that page or step within where the reader already is, W/A/S/D and #.

  • # and frame moves — keys.HASH (was CONVENTIONAL_NEXT_FRAME) is the # a viewdata reader presses to turn to the next frame of a page. frame_moves(has_previous, has_next) (was moving(back, on)) gives the keys a page of several frames answers; with_arrow_choices (was arrows_lead_where) copies each choice onto the arrow that points like its letter.

  • sequence, neighbours — the pages either side of this one in a run a menu offered, so a reader can step along without going back. request.neighbours is a Neighbours(previous, next) (was Arrival(preceding, following)).

  • next_page (was follows) — where # leads once a page’s frames have run out, so a title frame or the last frame of a guide answers the key a viewdata reader tries first. On PageLayout and Page.

  • shortcut — a key present on every frame that leads to a fixed address. layout.Shortcut: label (was says) is how the footer names it, with_arrow (was arrow) whether the matching cursor key leads there too.

  • DEFAULT_HOME (was _DEFAULT_HOME) — the sentinel a PageLayout or a one-call page uses for home when none is given: 0 leads to the service’s index. Distinct from home=None, which offers no way home. DefaultHome is its type. Public because sextile.pages shares it with sextile.layout.

  • home vs index — home is where a caller arrives when the line opens (Sextile(home=...), page 1 by default; a service opening on a title frame sets its own). Index is where the 0 key goes from every frame (Sextile(index=...), the same as home unless set apart). The footer word index is the label for that key.

  • CallNext (was Next) — the middleware continuation: a piece of middleware is async (request, build: CallNext) -> Page | None and calls build(request) to reach the rest of the chain. Starlette’s call_next; renamed off Next to stop it colliding with the *# Next command.

  • PageRequest — the request a handler answers. Kept PageRequest, not renamed to Request: the Page* family (PageRoute, PageRouter, PageAddress, PageFrame, PageLayout) is consistent, and the prefix keeps it clear of httpx’s Request in an app that imports both. Decided in Phase 2, not to be re-litigated.

  • fetch (was ask) — Sextile.fetch(target) builds a request for a page and answers it in process, for a test, a renderer or a tool with no socket. “fetch” is what a browser calls it; there is no HTTP verb to borrow.

  • idle timeout — an idle caller is released with on_timed_out(request, frame_index): the request is the page they were on, frame_index which frame of it. There was a Parting dataclass here; since it held only the frame it was dropped for a bare int.

  • session wire moments — viewdata.hangup.hangup_bytes (was parting.parting_bytes) repositions the cursor when the line drops, so a reader talking to their modem again has somewhere to type; Session.hangup() (was parting()) returns it. viewdata.idle_warning.idle_warning_bytes (was countdown.countdown_bytes) draws the bar that warns an idle caller before they are released.

  • session vs service state — session state is one caller’s own, lasting as long as the line is up (request.session, was a string-keyed mapping); service state is shared across callers for the life of the service (request.state). Both are keyed by StateKey: session state is writable, so a page may keep this caller’s own state; service state is a read-only view of what the lifespan opened, since a change would reach every caller at once.

  • connect (was calling) — sextile.testing.connect(app) opens a service, rings it up and closes it, yielding a Caller. The caller presses keys with caller.press(...) (was key) and reads caller.screen (was shown).

  • form — rows of a frame a reader types into, a field with furniture around it. forms.Form, forms.Field. TypeAhead (was Suggest) is a field with the best few matches beneath it, changing as the reader types; FieldSet (was Fields) is a form of several fields at once. A field accepts (was takes) the keys a reader may type into it. Its on_submit (was complete), footnote (was note), submit_label (was sends) and footer_items (was advice) each say what they are; the handler types are SubmitHandler (was Complete) and Footnote (was Note). A Form subclass overrides footer_items() (was named()) and reads top_row (was at), the row the layout placed it on.

  • command line — the sextile command and a service’s own are Click groups. standard_commands (was add_standard_subcommands) returns the shared render and serve commands a service adds to its group; form_options and listening_options (were add_form_arguments and add_listening_arguments) add their options to a command; load_application resolves a module:name. Click routes to each command, so the old run_standard dispatcher is gone.

  • line breaking — how wrapping.wrap_text and wrap_within lay the slack across the lines they break text into, chosen by Breaking (was the balanced= boolean): GREEDY fills each line in turn, PARAGRAPH balances with the last line free (the default, for body text), DISPLAY balances with the last line counted (for a centred string, so a short title breaks into two even lines rather than a full one and an orphan).

  • alignment — where something sits across the frame, chosen by composition.Align (START, CENTRE, END), re-exported at top level. One axis-neutral enum for everything placed: a Composition run, a Tile, and a Lines part’s align (Align replaced TextAlign at 0.5.0). Centre and end reuse the frame’s own centring, an odd spare cell going one fewer on the left.

  • tile — a rectangle of pre-solved teletext cells placed once, attributes included, from a solver such as sextants or a teletext-art editor. viewdata.tiles.Tile, built with Tile.from_bytes/from_rows, placed with Canvas.place(tile, row=, column=) or as a page part (parts=[tile]). Unlike RowWriter.mosaic, which inserts and charges its own attributes, a tile is placed cell-for-cell and pays for nothing — the solver already spent them.