Use docstring instead of variable definition

[ewenmcneill]

Inspired by a comment on the original version, it looks like we can use a docstring instead of a variable definition to hide the shell script. And by using : as suggested as the "placeholder" command in the shell script it is fairly readable.

From a quick test, it looks like this might work with a Bourne shell / Python2 / Python3, but needs some more testing. Test further, and if it works, then update the example.

The bonus of using a docstring to hide the data is that we can then use from __future__ ... in the Python code section.

""":" # Shell script, Python doc string; find Python interpreter

# Try the usual locations
for INTERPRETER in python3 python2 python; do
    PYTHON=$(command -v "${INTERPRETER}" 2>/dev/null)
    if [ -n "${PYTHON}" ]; then
       echo "Found Python in ${PYTHON}" >&2
       exec "${PYTHON}" "$0" "$@"
    fi
done

# Maybe we have Ansible or some other Python system program
# whose homework we can copy?
#
for PROGRAM in ansible; do
    PROGPATH=$(which "${PROGRAM}" 2>/dev/null)
    if [ -n "${PROGPATH}" -a -r "${PROGPATH}" ]; then
        PYTHON=$(head -1 $(command -v ansible) | sed 's/^#!//; s/^  *//; s/\/usr\/bin\/env //; s/ .*$//;')
        if [ -n "${PYTHON}" ]; then
           echo "Found Python in ${PYTHON}" >&2
           exec "${PYTHON}" "$0" "$@"
        fi
    fi
done

# Or we have some random OS default location
for PYTHON in /usr/libexec/platform-python; do
    if [ -x "${PYTHON}" ]; then
       echo "Found Python in ${PYTHON}" >&2
       exec "${PYTHON}" "$0" "$@"
    fi
done

echo "Sorry, I have no idea where Python is.  Is it even installed?!" >&2
exit 254
":""" # End of shell script, start of shared code

from __future__ import print_function
print("Hello World!")