Fish shell script which automatically activates the virtual environment when a particular directory becomes 'present working directory'. A map data structure would have been of good use, but its not present in fish shell. Though it is present in bash-4.x (see declare -A). I called it in /usr/local/share/fish/functions/cd.fish, inside cd function…

gistfile1.sh

# This automatically activates the virtual environment when a particular
# directory becomes 'present working directory'

function activatevirtualenvironment 
	# Activate virtual environment if some particular directory is pwd.

	set -l virtual_environment_dir $argv

	switch (pwd)
		case /Users/lafolle/hp/Awesome
			set -l virtual_environment_dir /Users/lafolle/hp/v
		case /Users/lafolle/FileFormatConversion
			set -l virtual_environment_dir /Users/lafolle/ffc
		case /Users/lafolle/hp/understands
			set -l virtual_environment_dir /Users/lafolle/hp/u
	end

	if not test $VIRTUAL_ENV = $virtual_environment_dir
		if test "(set -q VIRTUAL_ENV)" != "0" -a $VIRTUAL_ENV != "/Users/lafolle/Library/Enthought/Canopy_64bit/User"
			echo "Deactivating: " $VIRTUAL_ENV
			deactivate
		end
		echo "Activating :" $virtual_environment_dir
		. $virtual_environment_dir"/bin/activate.fish"
	end
end