Makefile.venv

VENV_NAME=venv
VENV=$(VENV_NAME)/bin
ACTIVATE_FILE=$(VENV)/activate
PYTHON=$(VENV)/python3

#
# Interactive shells
#

.PHONY: python
python: venv
	exec $(VENV)/python

.PHONY: ipython
ipython: $(VENV)/ipython
	exec $(VENV)/ipython

.PHONY: shell
shell: venv
	. $(VENV)/activate && exec $(notdir $(SHELL))

.PHONY: bash zsh
bash zsh: venv
	. $(VENV)/activate && exec $@

#
# Python interpreter detection
#

_PY_AUTODETECT_MSG=Detected Python interpreter: $(PY). Use PY environment variable to override

ifeq (ok,$(shell test -e /dev/null 2>&1 && echo ok))
NULL_STDERR=2>/dev/null
else
NULL_STDERR=2>NUL
endif

ifndef PY
_PY_OPTION:=python3
ifeq (ok,$(shell $(_PY_OPTION) -c "print('ok')" $(NULL_STDERR)))
PY=$(_PY_OPTION)
endif
endif

ifndef PY
_PY_OPTION:=$(VENVDIR)/bin/python
ifeq (ok,$(shell $(_PY_OPTION) -c "print('ok')" $(NULL_STDERR)))
PY=$(_PY_OPTION)
$(info $(_PY_AUTODETECT_MSG))
endif
endif

ifndef PY
_PY_OPTION:=python
ifeq (ok,$(shell $(_PY_OPTION) -c "print('ok')" $(NULL_STDERR)))
PY=$(_PY_OPTION)
$(info $(_PY_AUTODETECT_MSG))
endif
endif

ifndef PY
define _PY_AUTODETECT_ERR
Could not detect Python interpreter automatically.
Please specify path to interpreter via PY environment variable.
endef
$(error $(_PY_AUTODETECT_ERR))
endif

#
# Virtual environment
#

.PHONY: venv
venv:
	$(PY) -m venv $(VENV_NAME)
	$(VENV)/python -m pip install --upgrade pip setuptools wheel

.PHONY: venv-clean
venv-clean:
	rm -fr $(VENV_NAME)