Building Python on the Raspberry Pi2

## Building_Python_on_the_RPi2.bash
# Condensed and revised from Blake's site (unreachable currently):
# http://sowingseasons.com/blog/building-python-3-4-on-raspberry-pi-2.html

# Install prerequisites
sudo apt-get update
sudo apt-get upgrade -y
sudo apt-get install -y \
    build-essential libncursesw5-dev libgdbm-dev libc6-dev \
    zlib1g-dev libsqlite3-dev tk-dev libssl-dev openssl \
    libreadline6-dev liblzma-dev libbz2-dev libdb-dev
# Perhaps libreadline-dev will just as well above

# Choose a version:
    # Set version (3.4)
    export MYPYMAJ=3
    export MYPYMIN=4
    export MYPYPNT=3

    # Set version (3.5)
    export MYPYMAJ=3
    export MYPYMIN=5
    export MYPYPNT=1

    # Set version (2.7)
    export MYPYMAJ=2
    export MYPYMIN=7
    export MYPYPNT=11

# Get sources and build locally
export MYPYVER=${MYPYMAJ}.${MYPYMIN}.${MYPYPNT}
export MYPYREL=${MYPYMAJ}.${MYPYMIN}
mkdir -p ~/Projects
cd ~/Projects
wget --continue https://www.python.org/ftp/python/${MYPYVER}/Python-${MYPYVER}.tgz
tar -zxvf Python-${MYPYVER}.tgz
cd Python-${MYPYVER}
./configure
make -j 4

# Install any missing deps and run 'make' again.

# For the completists:
# Python 2.7 will warn about 'sunaudiodev' - ignore it:
# https://docs.python.org/2/library/sunaudio.html
# Likewise the ancient 'bsddb185' apparently can be ignored as well

# Alt install so we don't clobber the system's Python version!
# But whyyyyyy? http://stackoverflow.com/questions/16018463/difference-in-details-between-make-install-and-make-altinstall
# Details: https://hg.python.org/cpython/file/3.5/README#l149
#
# But, note that while 'python2' will still refer to the system's Python 2.7, 'python2.7' will now refer to yours!
# Presumably the same would be true for Python 3.2 were you to altinstall that.
# Pip will be similarly affected.
sudo make altinstall

# Test the Python you installed
python${MYPYREL}

# Check if Pip works already
pip${MYPYREL} --version

# If not, get Pip (superfluous anymore...)
cd ~/Projects
rm get-pip.py
wget https://bootstrap.pypa.io/get-pip.py
sudo python${MYPYREL} get-pip.py
pip${MYPYREL} --version