Re: proposed BASH_SOURCE_PATH

[Léa Gris]

> This needs to resolve symbolic links otherwise path will be that of the 
> symbolic link rather than that of the actual script file:

There are already ways to safely allow sourcing libraries relative to a 
bash script installation without adding features to Bash:

# Create tests and library folders
mkdir -p ./tests/libs

# Create main bash script command
cat > ./tests/real_bash_source_dir_test <<'BASH'
#!/usr/bin/env bash
real_source=$(realpath "${BASH_SOURCE[0]}")
real_source_dir=${real_source%/*}
include_path=$real_source_dir/libs

# shellcheck source=./libs/testlib.bash
source "$include_path/testlib.bash" || exit 1 # cannot load library
TestLib::hello
BASH

# Make it executable
chmod +x ./tests/real_bash_source_dir_test

# Create symbolic link to executable
ln -frs ./tests/real_bash_source_dir_test ./

# Create the library
cat > ./tests/libs/testlib.bash <<'BASH'
(return 0 2>/dev/null) && [ -n "${BASH_VERSION}" ] || exit 1
TestLib::hello() { printf 'Hello from TestLib\n';}
BASH

# Run command script from its real install dir
./tests/real_bash_source_dir_test

# Run command script from its symbolic link in current dir
./real_bash_source_dir_test

You can see it is able to source its library relative to its real 
installed path and it works regardless of if called from a symbolic link 
or directly from its installed dir.

--
Léa Gris