toolbox.sh: Make command-not-found errors more helpful

Command-not-found errors often occur because the user forgot to
include a module. In such cases, it would be helpful if the default
error message included suggestions for modules to include.

This commit adds a `command_not_found_handle()` function that
overrides bash's default behavior: aside of the usual error message,
this function will print all module names that the missing function
may be part of (as determined by its name) to stderr.

diff --git a/toolbox.sh b/toolbox.sh
index f690b01d09c18e410922540ef96ab078cbf1d296..b26729996a19e322be3afbbf42c4475cd0394904 100644 (file)
--- a/toolbox.sh
+++ b/toolbox.sh
@@ -1,7 +1,7 @@
 #!/bin/bash
 
 # toolbox.sh - Framework for modular bash scripts
-# Copyright (C) 2021 Matthias Kruk
+# Copyright (C) 2021-2022 Matthias Kruk
 #
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -36,6 +36,7 @@ __toolbox_init() {
        readonly -f have
        readonly -f _try_include
        readonly -f include
+       readonly -f command_not_found_handle
 
        return 0
 }
@@ -108,6 +109,40 @@ include() {
        return 0
 }
 
+command_not_found_handle() {
+       local command="$1"
+       # local args=("${@:2}") # not used
+
+       local searchpath
+       declare -A candidates
+
+       # Display the same message that bash usually would
+       echo "bash: $command: command not found" 1>&2
+
+       for searchpath in "${__TOOLBOX_MODULEPATH[@]}"; do
+               local module
+
+               while read -r module; do
+                       local module_name
+                       local prefix
+
+                       module_name="${module#"$searchpath"/}"
+                       module_name="${module_name%.sh}"
+                       prefix="${module_name//\//_}"
+
+                       if [[ "$command" == "$prefix"* ]]; then
+                               candidates["$module_name"]="$module"
+                       fi
+               done < <(find -L "$searchpath" -type f -iname "*.sh")
+       done
+
+       if (( ${#candidates[@]} > 0 )); then
+               echo "Did you forget to include a module? Possible candidates are: ${!candidates[*]}" 1>&2
+       fi
+
+       return 127
+}
+
 {
        if ! compgen -v | grep "^__TOOLBOX_INCLUDED$" &> /dev/null; then
                if ! __toolbox_init; then