struct-completion.el

struct-completion completes keyword slot arguments inside cl-defstruct constructor calls using runtime introspection. When you type (make-my-struct :), the package queries cl--class-slots and the constructor arglist to offer slot-aware candidates with type annotations, inheritance indicators, and per-slot documentation in the popup. It works with any completion UI that reads standard completion-at-point-functions properties: Corfu, Company, or the built-in default completion. The struct definition must be evaluated in the current session for candidates to appear.

The package handles all cl-defstruct constructor topologies: default make-TYPE constructors, renamed &key constructors, mixed positional-plus-keyword constructors (offering only the &key parameters), and :include inheritance chains of any depth. BOA constructors without &key are correctly ignored. A detector registry (struct-completion-detectors) allows extension to other keyword-plist-accepting forms without modifying the core.

Screenshots

Configuration

(use-package struct-completion
  :hook (emacs-lisp-mode . struct-completion-mode))

Examples:

You can test completion with these examples:

Inheritance

(cl-defstruct (http-request
               (:constructor http-request-create)
               (:copier nil))
  (url nil :type string
       :documentation "Fully qualified request URL including scheme.")
  (method :get :type (member :get :post :put :delete)
          :documentation "HTTP method keyword.
Defaults to `:get' for safe requests."))

(cl-defstruct (auth-request
               (:include http-request)
               (:constructor nil)
               (:constructor auth-request-create)
               (:constructor auth-request-quick (&key url token))
               (:copier nil))
  (token nil :type string
         :documentation "Bearer token for Authorization header.")
  (refresh-p nil :type boolean
             :documentation "Non-nil means automatically refresh on 401 responses."))

(http-request :)        ;; => original constructor -> 2 slots
(auth-request-create :) ;; => second constructor with inheritance -> 4 slots
(auth-request-quick :)  ;; => limited constructor, offers only :url, :token

After evaluating both forms, typing (auth-request-create :) offers:

Candidate	Annotation
:url	string ^
:method	(member :get ...) ^
:token	string
:refresh-p	boolean

Typing (auth-request-quick :) offers only :url and :token since the constructor arglist restricts the visible slots.

Selecting a candidate shows its :documentation string in the popup. Inherited slots from http-request are marked with ^.

By Order of Arguments (BOA) Constructors

Constructors with positional arguments and no &key produce no candidates. When a struct has both a BOA and a &key constructor, each is handled independently:

;; remember to eval the construct first in order to get completion
(cl-defstruct (vec3
               (:constructor nil)
               (:constructor vec3-kw)
               (:constructor vec3-boa (x y z)))
  (x 0.0 :type number)
  (y 0.0 :type number)
  (z 0.0 :type number))

(vec3-kw  :)   ;; => offers :x, :y, :z
(vec3-boa :)   ;; => no keyword completion (positional)

More info on BOA constructors here (weird name I know).

ROADMAP

Feature	Status	Description
cl-defstruct keyword completion	Done	Complete :slot keywords inside constructor calls
Type annotations	Done	Show slot :type specifier as completion suffix
Per-slot documentation popup	Done	Render :type, default, provenance, and :documentation in doc buffer
:include inheritance	Done	Inherited slots appear as candidates marked with ^
Ancestor metadata recovery	Done	Recover :type and :documentation lost by :include default overrides
BOA / mixed constructor handling	Done	Reject positional constructors; offer only &key params in mixed cases
Slot filtering	Done	Cross-reference slots against constructor arglist to exclude injections
Already-specified slot fading	In Progress	Visually dim slots already provided in the current call
EIEIO make-instance support	In Progress	Detect EIEIO class constructors and complete :initarg keywords
Internal slot hiding	Planned	Optionally suppress candidates starting with :-

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