toolbox: Implement toolbox initialization and module loading

When writing shell scripts, I often find myself copying or rewriting
functions because bash does not provide a mechanism to easily reuse
code. This commit adds a mechanism for loadable bash "modules".

diff --git a/toolbox.sh b/toolbox.sh
new file mode 100644 (file)
index 0000000..9f419c4
--- /dev/null
+++ b/toolbox.sh
@@ -0,0 +1,78 @@
+#!/bin/bash
+
+#
+# Toolbox - A set of unsophisticated bash "modules"
+# Copyright (C) 2021 - Matthias Kruk <m@m10k.eu>
+#
+
+__toolbox_init() {
+       export TOOLBOX_PATH="$(dirname "$(realpath "${BASH_SOURCE[0]}")")"
+       export TOOLBOX_HOME="$HOME/.toolbox"
+
+       declare -ag __TOOLBOX_INCLUDED=()
+
+       return 0
+}
+
+have() {
+       local module
+       local included
+
+       module="$1"
+
+       for included in "${__TOOLBOX_INCLUDED[@]}"; do
+               local modpath
+
+               modpath="$TOOLBOX_PATH/include/$module.sh"
+
+               if [[ "$included" == "$modpath" ]]; then
+                       return 0
+               fi
+       done
+
+       return 1
+}
+
+include() {
+       local err
+       local module
+
+       err=0
+
+       for module in "$@"; do
+               local modpath
+
+               if have "$module"; then
+                       continue
+               fi
+
+               modpath="$TOOLBOX_PATH/include/$module.sh"
+
+               if ! . "$modpath"; then
+                       echo "ERROR: Could not load $modpath" 1>&2
+                       err=1
+                       continue
+               fi
+
+               if ! __init; then
+                       echo "ERROR: Could not initialize $module" 1>&2
+                       err=1
+               else
+                       __TOOLBOX_INCLUDED+=("$modpath")
+               fi
+
+               unset -f __init
+       done
+
+       return "$err"
+}
+
+{
+       if ! compgen -v | grep "^__TOOLBOX_INCLUDED$" &> /dev/null; then
+               if ! __toolbox_init; then
+                       echo "Could not initialize toolbox" 1>&2
+               fi
+
+               unset -f __toolbox_init
+       fi
+}