Tempel is a tiny template package for Emacs, which uses the syntax of the Emacs Tempo library. Tempo is an ancient temple of the church of Emacs. It is 27 years old, but still in good shape since it successfully resisted change over the decades. However it may look a bit dusty here and there. Therefore we present Tempel, a modernized implementation of Tempo.
Tempel comes with three commands for template expansion:
tempel-complete
completes a template name at point in the buffer and subsequently expands the template. If called non-interactively the function behaves like a Capf and can be added tocompletion-at-point-functions
.tempel-expand
expands an exactly matching template name at point in the buffer. If called non-interactively the function behaves like a Capf and can be added tocompletion-at-point-functions
.tempel-insert
selects a template by name and insert it into the current buffer.
For the completion at point commands tempel-complete
and tempel-expand
, you may
want to give my Corfu completion at point popup UI a try. After inserting the
template you can move between the visible template fields with the keys M-{
, M-}
or C-up/down
which are normally bound to forward/backward-paragraph
. Tempel
temporarily remaps these commands to tempel-next/previous
. The key
bindings are defined in the tempel-map
keymap. You can customize them there. As
soon as you move before (behind) the first (last) field, the fields are
finalized.
The package is available on GNU ELPA and MELPA and can be installed with
package-install
. The following example configuration relies on use-package
.
;; Configure Tempel
(use-package tempel
;; Require trigger prefix before template name when completing.
;; :custom
;; (tempel-trigger-prefix "<")
:bind (("M-+" . tempel-complete) ;; Alternative tempel-expand
("M-*" . tempel-insert))
:init
;; Setup completion at point
(defun tempel-setup-capf ()
;; Add the Tempel Capf to `completion-at-point-functions'.
;; `tempel-expand' only triggers on exact matches. Alternatively use
;; `tempel-complete' if you want to see all matches, but then you
;; should also configure `tempel-trigger-prefix', such that Tempel
;; does not trigger too often when you don't expect it. NOTE: We add
;; `tempel-expand' *before* the main programming mode Capf, such
;; that it will be tried first.
(setq-local completion-at-point-functions
(cons #'tempel-expand
completion-at-point-functions)))
(add-hook 'prog-mode-hook 'tempel-setup-capf)
(add-hook 'text-mode-hook 'tempel-setup-capf)
;; Optionally make the Tempel templates available to Abbrev,
;; either locally or globally. `expand-abbrev' is bound to C-x '.
;; (add-hook 'prog-mode-hook #'tempel-abbrev-mode)
;; (global-tempel-abbrev-mode)
)
;; Optional: Use the Corfu completion UI
(use-package corfu
:init
(global-corfu-mode))
The templates are defined in a Lisp data file configured by tempel-path
. Lisp
data files are files containing Lisp s-expressions (see lisp-data-mode
). By
default the file ~/.config/emacs/templates
is used. The templates are grouped by
major mode with an optional :when
condition. Each template is a list in the
concise form of the Emacs Tempo syntax. The first element of each list is the
name of the template. Behind the name, the Tempo syntax elements follow.
In addition, each template may specify a :pre
and/or :post
key with a FORM that is
evaluated before the template is expanded or after it is finalized, respectively. The
:post
form is evaluated in the lexical scope of the template, which means that it can
access the template’s named fields.
;; ~/.config/emacs/templates
fundamental-mode ;; Available everywhere
(today (format-time-string "%Y-%m-%d"))
prog-mode
(fixme (if (derived-mode-p 'emacs-lisp-mode) ";; " comment-start) "FIXME ")
(todo (if (derived-mode-p 'emacs-lisp-mode) ";; " comment-start) "TODO ")
(bug (if (derived-mode-p 'emacs-lisp-mode) ";; " comment-start) "BUG ")
(hack (if (derived-mode-p 'emacs-lisp-mode) ";; " comment-start) "HACK ")
latex-mode
(begin "\\begin{" (s env) "}" r> n> "\\end{" (s env) "}")
(frac "\\frac{" p "}{" q "}")
(enumerate "\\begin{enumerate}\n\\item " r> n> "\\end{enumerate}")
(itemize "\\begin{itemize}\n\\item " r> n> "\\end{itemize}")
lisp-mode emacs-lisp-mode ;; Specify multiple modes
(lambda "(lambda (" p ")" n> r> ")")
emacs-lisp-mode
(autoload ";;;###autoload")
(pt "(point)")
(lambda "(lambda (" p ")" n> r> ")")
(var "(defvar " p "\n \"" p "\")")
(local "(defvar-local " p "\n \"" p "\")")
(const "(defconst " p "\n \"" p "\")")
(custom "(defcustom " p "\n \"" p "\"" n> ":type '" p ")")
(face "(defface " p " '((t :inherit " p "))\n \"" p "\")")
(group "(defgroup " p " nil\n \"" p "\"" n> ":group '" p n> ":prefix \"" p "-\")")
(macro "(defmacro " p " (" p ")\n \"" p "\"" n> r> ")")
(alias "(defalias '" p " '" p ")")
(fun "(defun " p " (" p ")\n \"" p "\"" n> r> ")")
(iflet "(if-let (" p ")" n> r> ")")
(whenlet "(when-let (" p ")" n> r> ")")
(iflet* "(if-let* (" p ")" n> r> ")")
(whenlet* "(when-let* (" p ")" n> r> ")")
(andlet* "(and-let* (" p ")" n> r> ")")
(cond "(cond" n "(" q "))" >)
(pcase "(pcase " (p "scrutinee") n "(" q "))" >)
(let "(let (" p ")" n> r> ")")
(let* "(let* (" p ")" n> r> ")")
(rec "(letrec (" p ")" n> r> ")")
(dotimes "(dotimes (" p ")" n> r> ")")
(dolist "(dolist (" p ")" n> r> ")")
(loop "(cl-loop for " p " in " p " do" n> r> ")")
(command "(defun " p " (" p ")\n \"" p "\"" n> "(interactive" p ")" n> r> ")")
(advice "(defun " (p "adv" name) " (&rest app)" n> p n> "(apply app))" n>
"(advice-add #'" (p "fun") " " (p ":around") " #'" (s name) ")")
(provide "(provide '" (file-name-base (or (buffer-file-name) (buffer-name))) ")" n
";;; " (file-name-nondirectory (or (buffer-file-name) (buffer-name))) " ends here" n)
eshell-mode
(for "for " (p "i") " in " p " { " q " }")
(while "while { " p " } { " q " }")
(until "until { " p " } { " q " }")
(if "if { " p " } { " q " }")
(ife "if { " p " } { " p " } { " q " }")
(unl "unless { " p " } { " q " }")
(unle "unless { " p " } { " p " } { " q " }")
text-mode
(cut "--8<---------------cut here---------------start------------->8---" n r n
"--8<---------------cut here---------------end--------------->8---" n)
(asciibox "+-" (make-string (length str) ?-) "-+" n
"| " (s str) " |" n
"+-" (make-string (length str) ?-) "-+" n)
(rot13 (p "plain text" text) n "----" n (rot13 text))
(calc (p "taylor(sin(x),x=0,3)" formula) n "----" n (format "%s" (calc-eval formula)))
rst-mode
(title (make-string (length title) ?=) n (p "Title: " title) n (make-string (length title) ?=) n)
java-mode
(class "public class " (p (file-name-base (or (buffer-file-name) (buffer-name)))) " {" n> r> n "}")
c-mode :when (re-search-backward "^\\S-*$" (line-beginning-position) 'noerror)
(inc "#include <" (p (concat (file-name-base (or (buffer-file-name) (buffer-name))) ".h")) ">")
(incc "#include \"" (p (concat (file-name-base (or (buffer-file-name) (buffer-name))) ".h")) "\"")
org-mode
(title "#+title: " p n "#+author: Daniel Mendler" n "#+language: en" n n)
(quote "#+begin_quote" n> r> n> "#+end_quote")
(example "#+begin_example" n> r> n> "#+end_example")
(center "#+begin_center" n> r> n> "#+end_center")
(comment "#+begin_comment" n> r> n> "#+end_comment")
(verse "#+begin_verse" n> r> n> "#+end_verse")
(src "#+begin_src " p n> r> n> "#+end_src" :post (org-edit-src-code))
(elisp "#+begin_src emacs-lisp" n> r> n "#+end_src" :post (org-edit-src-code))
;; Local Variables:
;; mode: lisp-data
;; outline-regexp: "[a-z]"
;; End:
All the Tempo syntax elements are fully supported. The syntax elements are
described in detail in the docstring of tempo-define-template
in tempo.el. We
document the important ones here:
- “string” Inserts a string literal.
p
Inserts an unnamed placeholder field.n
Inserts a newline.>
Indents withindent-according-to-mode
.r
Inserts the current region. If no region is active, quits the containing template when jumped to.r>
Acts liker
, but indent region.n>
Inserts a newline and indents.&
Insert newline if there is only whitespace between line start and point.%
Insert newline if there is only whitespace between point and line end.o
Like%
but leaves the point before newline.(s NAME)
Inserts a named field.(p PROMPT <NAME> <NOINSERT>)
Insert an optionally named field with a prompt. ThePROMPT
is displayed directly in the buffer as default value. IfNOINSERT
is non-nil, no field is inserted. Then the minibuffer is used for prompting and the value is bound toNAME
.(r PROMPT <NAME> <NOINSERT>)
Insert region or act like(p ...)
.(r> PROMPT <NAME> <NOINSERT>)
Act like(r ...)
, but indent region.
Furthermore Tempel supports syntax extensions:
(p FORM <NAME> <NOINSERT>)
Likep
described above, butFORM
is evaluated.(FORM ...)
Other Lisp forms are evaluated. Named fields are lexically bound.q
Quits the containing template when jumped to.
Use caution with templates which execute arbitrary code!
Tempel supports custom user elements via the configuration variable
tempel-user-elements
. As a demonstration we add the element (i template)
to
include templates by name in another template.
(defun tempel-include (elt)
(when (eq (car-safe elt) 'i)
(if-let (template (alist-get (cadr elt) (tempel--templates)))
(cons 'l template)
(message "Template %s not found" (cadr elt))
nil)))
(add-to-list 'tempel-user-elements #'tempel-include)
The following example templates uses the newly defined include element.
(header ";;; " (or (buffer-file-name) (buffer-name)) " -- " p
" -*- lexical-binding: t -*-" n n)
(provide "(provide '" (file-name-base (or (buffer-file-name) (buffer-name))) ")" n
";;; " (file-name-nondirectory (or (buffer-file-name) (buffer-name))) " ends here" n)
(package (i header) r n n (i provide))
Tempel offers a flexible mechanism for providing the templates, which are
applicable to the current context. The variable tempel-template-sources
specifies a list of sources or a single source. A source can either be a
function, which should return a list of applicable templates, or the symbol of a
variable, which holds a list of templates, which apply to the current context.
By default, Tempel configures only the source tempel-path-templates
. You may
want to add global or local template variables to your user configuration:
(defvar my-global-templates
'((example "Global example template"))
"My global templates.")
(defvar-local my-local-templates nil
"Buffer-local templates.")
(add-to-list 'tempel-template-sources 'my-global-templates)
(add-to-list 'tempel-template-sources 'my-local-templates)
Tempel can hook into Abbrev by enabling the tempel-abbrev-mode
in a buffer or by
enabling the global-tempel-abbrev-mode
. Then the Tempel templates will be
available via expand-abbrev
which is usually bound to C-x '
.
Important templates can be bound to a key with the small utility macro
tempel-key
which accepts three arguments, a key, a template or name and
optionally a map.
(tempel-key "C-c t f" fun emacs-lisp-mode-map)
(tempel-key "C-c t d" (format-time-string "%Y-%m-%d"))
Internally tempel-key
uses tempel-insert
to trigger the insertion. Depending on
the style of your user configuration you may want to write your own helper
macros, which allow you to conveniently bind templates via use-package, general
or similar keybinding packages.
Tempel does not come with readily available snippet collections, unlike the YASnippet library. Try Tempel if you like small and simple packages. With Tempel you write your templates in Lisp syntax, which from my perspective fits well to the hackable nature of Emacs. Tempel took inspiration from the Tempo-Snippets package by Nikolaj Schumacher (GitHub link).
There are plenty of alternative packages which provide abbreviation or snippet expansion.
- abbrev.el: Abbreviation expansion, builtin
- expand.el: Abbreviation expansion, builtin
- skeleton.el: Lisp syntax for templates, builtin
- tempo.el: Lisp syntax for templates, builtin
- aas.el: Auto activating snippets
- cdlatex.el: Fast LaTeX insertion
- laas.el: Latex auto activating snippets
- muban.el: Lightweight template expansion
- placeholder.el: Treat buffers as templates
- skempo.el: Unifies the Skeleton and Tempo configuration
- snippet.el: Original snippet mode
- tempo-snippets.el: snippet.el-like interface for Tempo
- yasnippet.el: The most popular template system
Since this package is part of GNU ELPA contributions require a copyright assignment to the FSF.