Makefile rules to activate Python virtualenv for the whole Makefile

Makefile

# get makefile's own path
mkfile_path := $(abspath $(lastword $(MAKEFILE_LIST)))
mkfile_dir := $(dir $(mkfile_path))

# add virtualenv in folder "virtualenv" to the path
export PATH := $(mkfile_dir)/virtualenv/bin:$(PATH)
export VIRTUAL_ENV=$(mkfile_dir)/virtualenv

example: something.py
	python something.py # <- this will be called with virtualenv activated