Cask can be likened to venv
or maven
for Emacs Lisp development,
although, as with all things emacs, is decidedly less sophisticated
(but no less arcane).
Cask provisions dependencies within a sandbox via a user-defined
“Cask” file analogous to requirements-dev.txt
or pom.xml
.
Cask does not absolve you of having to learn emacs’s command flags. Cask only constructs the sandbox, one for each version of emacs you choose to test.
git clone https://github.com/cask/cask
make -C cask install
With just this baseline “Cask” file, you can run most of the commands described in http://cask.readthedocs.io.
(source gnu)
(source melpa)
(package-file "your-main-file.el")
The EMACS
environment variable governs which emacs binary to test. For example,
the following runs ert tests under an older emacs:
EMACS=emacs-25.3 cask emacs --batch -l mytest.el -f ert-run-tests-batch
We have deprecated the cask exec
invocation, and consequently no
longer recommend cask exec ert-runner
nor cask exec ecukes
.
Egregious boilerplate follows:
export EMACS ?= $(shell which emacs)
CASK_DIR := $(shell cask package-directory)
$(CASK_DIR): Cask
cask install
@touch $(CASK_DIR)
.PHONY: cask
cask: $(CASK_DIR)
.PHONY: compile
compile: cask
cask emacs -batch -L . -L test \
--eval "(setq byte-compile-error-on-warn t)" \
-f batch-byte-compile $$(cask files); \
(ret=$$? ; cask clean-elc && exit $$ret)
.PHONY: test
test: compile
cask emacs --batch -L . -L test -l readme-test -f ert-run-tests-batch
Cask, in conjunction with setup-emacs, is commonly used in Github Actions. Egregious boilerplate follows:
jobs:
test:
runs-on: ubuntu-latest
strategy:
matrix:
emacs-version:
- 26.3
- 27.2
- 28.2
steps:
- uses: actions/checkout@v2
- uses: purcell/setup-emacs@master
with:
version: ${{ matrix.emacs-version }}
- uses: actions/cache@v2
id: cache-cask-packages
with:
path: .cask
key: cache-cask-packages-000
- uses: actions/cache@v2
id: cache-cask-executable
with:
path: ~/.cask
key: cache-cask-executable-000
- uses: cask/setup-cask@master
if: steps.cache-cask-executable.outputs.cache-hit != 'true'
with:
version: snapshot
- run: echo "$HOME/.cask/bin" >> $GITHUB_PATH
- Why does install “not know where to install”?
- After assaying cross-platform schemes like
systemd-path
andXDG_DATA_HOME
to figure out a suitable install directory, Cask resorts to the old, unspoken standbys of~/.local/bin
and~/bin
. If neither of those are present, thenmake install
gives up with that error. I couldn’t determine a more standard method last I asked stackoverflow.com. - Why is everything you say inconsistent with cask.readthedocs.io?
- I would disregard nearly everything at cask.readthedocs.io, especially the Quickstart page. In particular, I would not
require cask
in your dot.emacs since cask is now largely a command-line tool independent of whatever you do within emacs. If you are callingcask-initialize
in your dot.emacs or harken back to the bygone era of pallet, I’m afraid you’re on your own. - Why must I replicate dependencies in the Cask file?
- You mustn’t, but probably more than half of Cask deployments in the wild needlessly do.
cask list
automatically shows your package’s dependencies if you specify them pro forma in aPackage-Requires
header. The oft-confused development stanza is analogous torequirements-dev.txt
. Only packages required by your testing apparatus, e.g.,ert-runner
, should be added there. - Doesn’t Cask make things more complicated?
- Yes, because it forces you to test your package under multiple versions of emacs. Most packages don’t do any testing at all, which is why emacs has lost credibility with the computing public.
- Is Cask a vassal of MELPA?
- Yes, Cask’s early development history is intertwined with that of MELPA’s package-build. Cask employs that module for all packaging tasks including dependency provisioning.