Added comments and changed internal variable names

init.fish

@@ -1,44 +1,65 @@
+################################################################################
+############  AutoVenv for Fish Shell v2019.03.28 by @TimothyBrown  ############
+################################################################################
+## AutoVenv Settings
 if status is-interactive
     test -z "$autovenv_announce"
         and set -g autovenv_announce "yes"
     test -z "$autovenv_enable"
         and set -g autovenv_enable "yes"
+end
 
-    function autovenv --on-variable PWD -d "Automatic activation of Python virtual enviroments"
-        test ! "$autovenv_enable" = "yes"
-            and return
-        for autovenv_find_dir in (string split -n '/' "$PWD")
-            set autovenv_find_tree "$autovenv_find_tree/$autovenv_find_dir"
-            if test -e "$autovenv_find_tree/bin/activate.fish"
-                set autovenv_source "$autovenv_find_tree/bin/activate.fish"
-                if test "$autovenv_announce" = "yes"
-                    set autovenv_name_old "$autovenv_name"
-                    set -g autovenv_name (basename "$autovenv_find_tree")
-                end
-                break
+## AutoVenv Function
+# Activates on directory changes.
+function autovenv --on-variable PWD -d "Automatic activation of Python virtual environments"
+    # Check for the enable flag and make sure we're running interactive, if not return.
+    test ! "$autovenv_enable" = "yes"
+        or not status is-interactive
+        and return
+    # We start by splitting our CWD path into individual elements and iterating over each element.
+    # If our CWD is `/opt/my/hovercraft/eels` we split it into a variable containing 4 entries:
+    # `opt`, `my`, `hovercraft` and `eels`. We then build back up the path by iterating over the list
+    # and adding each element to the previous one. (We start with `/opt`, then `/opt/my` and so on.)
+    # During each run through the loop we test for a sub-directory/file called `bin/activate.fish`. If a
+    # venv is found we go ahead and break out of the loop, otherwise continue. We go through all of this
+    # instead of just checking the CWD to handle cases where the user moves into a sub-directory of the venv.
+    for _dir in (string split -n '/' "$PWD")
+        set -l _tree "$_tree/$_dir"
+        if test -e "$_tree/bin/activate.fish"
+            set _source "$_tree/bin/activate.fish"
+            if test "$autovenv_announce" = "yes"
+                set -g __autovenv_old $__autovenv_new
+                set -g __autovenv_new (basename $_tree)
             end
+            break
+        end
+    end
+    # If we're *not* in an active venv and the venv source dir exists we activate it and return.
+    if test -z "$VIRTUAL_ENV" -a -e "$_source"
+        source "$_source"
+        if test "$autovenv_announce" = "yes"
+            echo "Activated Virtual Environment ($__autovenv_new)"
         end
-        if test -z "$VIRTUAL_ENV" -a -e "$autovenv_source"
-            source "$autovenv_source"
+    # Next we check to see if we're already in an active venv. If so we proceed with further tests.
+    else if test -n "$VIRTUAL_ENV"
+        # Check to see if our CWD is inside the venv directory.
+        set _dir (string match -n "$VIRTUAL_ENV*" "$PWD")
+        # If we're no longer inside the venv dirctory deactivate it and return.
+        if test -z "$_dir" -a ! -e "$_source"
+            deactivate
             if test "$autovenv_announce" = "yes"
-                echo "Activated Virtual Enviroment ($autovenv_name)"
+                echo "Deactivated Virtual Enviroment ($__autovenv_new)"
+                set -e __autovenv_new
+                set -e __autovenv_old
             end
-        else if test -n "$VIRTUAL_ENV"
-            set autovenv_dir (string match -n "$VIRTUAL_ENV*" "$PWD")
-            if test -z "$autovenv_dir" -a ! -e "$autovenv_source"
-                deactivate
-                if test "$autovenv_announce" = "yes"
-                    echo "Deactivated Virtual Enviroment ($autovenv_name)"
-                    set -e autovenv_name
-                    set -e autovenv_name_old
-                end
-            else if test -z "$autovenv_dir" -a -e "$autovenv_source"
-                deactivate
-                source "$autovenv_source"
-                if test "$autovenv_announce" = "yes"
-                    echo "Switched Virtual Enviroments ($autovenv_name_old => $autovenv_name)"
-                end
+        # If we've switched into a different venv directory, deactivate the old and activate the new.
+        else if test -z "$_dir" -a -e "$_source"
+            deactivate
+            source "$_source"
+            if test "$autovenv_announce" = "yes"
+                echo "Switched Virtual Environments ($__autovenv_old => $__autovenv_new)"
             end
         end
     end
-end
+end
+################################################################################