Avoid loops when loading libraries

The library `preexec` requires complete control over the DEBUG trap and
PROMPT_COMMAND, but it was being loaded in the library loop. When evaluating
options, I came to the conclusion that we don't have enough libraries to
justify this premature optimization, so I've flattened as much of the sourcing
as possible and added comments to explain their purpose, hoping that future
maintainers will use these to guide their decisions when adding more libraries
or changing the load order.

bash_it.sh

@@ -1,9 +1,7 @@
 #!/usr/bin/env bash
-# Initialize Bash It
-BASH_IT_LOG_PREFIX="core: main: "
 
 # Only set $BASH_IT if it's not already set
-if [ -z "$BASH_IT" ]; then
+if [[ -z "$BASH_IT" ]]; then
 	# Setting $BASH to maintain backwards compatibility
 	export BASH_IT=$BASH
 	BASH="$(bash -c 'echo $BASH')"
@@ -11,107 +9,121 @@ if [ -z "$BASH_IT" ]; then
 	BASH_IT_OLD_BASH_SETUP=true
 fi
 
-# Load composure first, so we support function metadata
+# Load composure first, to support function metadata, then create our custom attributes.
 # shellcheck disable=SC1090
 source "${BASH_IT}"/vendor/github.com/erichs/composure/composure.sh
+cite _about _param _example _group _author _version
+cite about-alias about-completion about-plugin
 
-# We need to load logging module first as well in order to be able to log
+# Next, load our logging library so we can give useful feedback to the user
 # shellcheck source=./lib/log.bash
 source "${BASH_IT}/lib/log.bash"
 
-# We can only log it now
+BASH_IT_LOG_PREFIX='core: main: '
-[ -z "$BASH_IT_OLD_BASH_SETUP" ] || _log_warning "BASH_IT variable not initialized, please upgrade your bash-it version and reinstall it!"
+
+# Check for old installations
+if [[ -n "$BASH_IT_OLD_BASH_SETUP" ]]; then
+	_log_warning "BASH_IT variable not initialized, please upgrade your bash-it version and reinstall it!"
+fi
 
 # For backwards compatibility, look in old BASH_THEME location
-if [ -z "$BASH_IT_THEME" ]; then
+if [[ -z "$BASH_IT_THEME" ]]; then
 	_log_warning "BASH_IT_THEME variable not initialized, please upgrade your bash-it version and reinstall it!"
 	export BASH_IT_THEME="$BASH_THEME"
 	unset BASH_THEME
 fi
 
-# support 'plumbing' metadata
+# Load the base libraries ...
-cite _about _param _example _group _author _version
+# Note: Ordering is important and intentional
-cite about-alias about-plugin about-completion
 
-# libraries, but skip appearance (themes) for now
+# "utilities" - internal functions meant for use within the bash-it codebase
-_log_debug "Loading libraries(except appearance)..."
+BASH_IT_LOG_PREFIX='lib: utilities: '
-LIB="${BASH_IT}/lib/*.bash"
+_log_debug 'Loading library file ...'
-APPEARANCE_LIB="${BASH_IT}/lib/appearance.bash"
+# shellcheck source=./lib/utilities.bash
-for _bash_it_config_file in $LIB; do
+source "${BASH_IT}/lib/utilities.bash"
-	if [ "$_bash_it_config_file" != "$APPEARANCE_LIB" ]; then
-		filename=${_bash_it_config_file##*/}
-		filename=${filename%.bash}
-		BASH_IT_LOG_PREFIX="lib: ${filename}: "
-		_log_debug "Loading library file..."
-		# shellcheck disable=SC1090
-		source "$_bash_it_config_file"
-	fi
-done
 
-# Load vendors
+# "helpers" - generic functions meant for generic use by end users,
-BASH_IT_LOG_PREFIX="vendor: "
+#             often wrappers of functions found in utilities
-for _bash_it_vendor_init in "${BASH_IT}"/vendor/init.d/*.bash; do
+BASH_IT_LOG_PREFIX='lib: helpers: '
-	_log_debug "Loading \"$(basename "${_bash_it_vendor_init}" .bash)\"..."
+_log_debug 'Loading library file ...'
-	# shellcheck disable=SC1090
+# shellcheck source=./lib/helpers.bash
-	source "${_bash_it_vendor_init}"
+source "${BASH_IT}/lib/helpers.bash"
-done
+
-unset _bash_it_vendor_init
+# "search" - allows end users to search for matching aliases, plugins and completions in bash-it
+BASH_IT_LOG_PREFIX='lib: search: '
+_log_debug 'Loading library file ...'
+# shellcheck source=./lib/search.bash
+source "${BASH_IT}/lib/search.bash"
+
+# Load aliases, completion, plugins ...
+BASH_IT_LOG_PREFIX='core: main: '
 
-BASH_IT_LOG_PREFIX="core: main: "
 # Load the global "enabled" directory
 # "family" param is empty so that files get sources in glob order
 # shellcheck source=./scripts/reloader.bash
 source "${BASH_IT}/scripts/reloader.bash"
 
 # Load enabled aliases, completion, plugins
-for file_type in "aliases" "plugins" "completion"; do
+for file_type in 'aliases' 'plugins' 'completion'; do
 	# shellcheck source=./scripts/reloader.bash
-	source "${BASH_IT}/scripts/reloader.bash" "skip" "$file_type"
+	source "${BASH_IT}/scripts/reloader.bash" 'skip' "$file_type"
 done
 
 # Load theme, if a theme was set
 if [[ -n "${BASH_IT_THEME}" ]]; then
 	_log_debug "Loading \"${BASH_IT_THEME}\" theme..."
+
 	# Load colors and helpers first so they can be used in base theme
-	BASH_IT_LOG_PREFIX="themes: colors: "
+	BASH_IT_LOG_PREFIX='themes: colors: '
+	_log_debug 'Loading theme file ...'
 	# shellcheck source=./themes/colors.theme.bash
 	source "${BASH_IT}/themes/colors.theme.bash"
-	BASH_IT_LOG_PREFIX="themes: githelpers: "
+
+	BASH_IT_LOG_PREFIX='themes: githelpers: '
+	_log_debug 'Loading theme file ...'
 	# shellcheck source=./themes/githelpers.theme.bash
 	source "${BASH_IT}/themes/githelpers.theme.bash"
-	BASH_IT_LOG_PREFIX="themes: p4helpers: "
+
+	BASH_IT_LOG_PREFIX='themes: p4helpers: '
+	_log_debug 'Loading theme file ...'
 	# shellcheck source=./themes/p4helpers.theme.bash
 	source "${BASH_IT}/themes/p4helpers.theme.bash"
-	BASH_IT_LOG_PREFIX="themes: command_duration: "
+
+	BASH_IT_LOG_PREFIX='themes: command_duration: '
+	_log_debug 'Loading theme file ...'
 	# shellcheck source=./themes/command_duration.theme.bash
 	source "${BASH_IT}/themes/command_duration.theme.bash"
-	BASH_IT_LOG_PREFIX="themes: base: "
+
+	BASH_IT_LOG_PREFIX='themes: base: '
+	_log_debug 'Loading theme file ...'
 	# shellcheck source=./themes/base.theme.bash
 	source "${BASH_IT}/themes/base.theme.bash"
 
-	BASH_IT_LOG_PREFIX="lib: appearance: "
+	BASH_IT_LOG_PREFIX='lib: appearance: '
+	_log_debug 'Loading library file ...'
 	# appearance (themes) now, after all dependencies
 	# shellcheck source=./lib/appearance.bash
-	source "$APPEARANCE_LIB"
+	source "${BASH_IT}/lib/appearance.bash"
 fi
 
-BASH_IT_LOG_PREFIX="core: main: "
+# Load custom components ...
-_log_debug "Loading custom aliases, completion, plugins..."
+
-for file_type in "aliases" "completion" "plugins"; do
+BASH_IT_LOG_PREFIX='core: main: '
-	if [ -e "${BASH_IT}/${file_type}/custom.${file_type}.bash" ]; then
+_log_debug 'Loading custom aliases, completion, plugins...'
+for file_type in 'aliases' 'completion' 'plugins'; do
+	if [[ -e "${BASH_IT}/${file_type}/custom.${file_type}.bash" ]]; then
 		BASH_IT_LOG_PREFIX="${file_type}: custom: "
-		_log_debug "Loading component..."
+		_log_debug 'Loading component...'
 		# shellcheck disable=SC1090
 		source "${BASH_IT}/${file_type}/custom.${file_type}.bash"
 	fi
 done
 
-# Custom
 BASH_IT_LOG_PREFIX="core: main: "
 _log_debug "Loading general custom files..."
 CUSTOM="${BASH_IT_CUSTOM:=${BASH_IT}/custom}/*.bash ${BASH_IT_CUSTOM:=${BASH_IT}/custom}/**/*.bash"
 for _bash_it_config_file in $CUSTOM; do
-	if [ -e "${_bash_it_config_file}" ]; then
+	if [[ -e "${_bash_it_config_file}" ]]; then
 		filename=$(basename "${_bash_it_config_file}")
 		filename=${filename%*.bash}
 		BASH_IT_LOG_PREFIX="custom: $filename: "
@@ -137,7 +149,6 @@ elif [ -s /Applications/Preview.app ]; then
 fi
 
 # Load all the Jekyll stuff
-
 if [ -e "$HOME/.jekyllconfig" ]; then
 	# shellcheck disable=SC1090
 	. "$HOME/.jekyllconfig"
@@ -155,5 +166,17 @@ if ! command -v reload &> /dev/null && [ -n "$BASH_IT_RELOAD_LEGACY" ]; then
 	esac
 fi
 
+# Now that everything is loaded and configured, load the previewer
+BASH_IT_LOG_PREFIX='lib: preview: '
+# and the associated preview script
+# shellcheck source=./lib/preview.bash
+source "${BASH_IT}/lib/preview.bash"
+
 # Disable trap DEBUG on subshells - https://github.com/Bash-it/bash-it/pull/1040
 set +T
+
+# Finally, load preexec directly from vendor.
+# This has to be last because it wants to have full control over DEBUG trap and PROMPT_COMMAND
+BASH_IT_LOG_PREFIX='vendor: bash-preexec: '
+# shellcheck source=./vendor/github.com/rcaloras/bash-preexec/bash-preexec.sh
+source "${BASH_IT}/vendor/github.com/rcaloras/bash-preexec/bash-preexec.sh"