How to specify argument value from Bash/ZSH alias?

In my .zshrc I have the following aliases

alias ls="colorls"
alias l="colorls -1"
alias la="colorls -a"
alias ld="colorls -d"
alias lf="colorls -f"
alias lt="colorls --tree"
alias ltd="colorls --tree=$1"`

I have used the ltd alias to run colorls with the tree argument which requires an integer for tree depth.

I was hoping that by running ltd 5 (or any specified number) I would be aliasing colorls --tree=5, but this appears to be incompatible.

Additionally colorls requires the integer to be specified directly after the equals sign without a space. This means that alias ltd="colorls --tree=" doesn't work either.

How can I perform this method of aliasing properly? Thank you

You can just use a shell function instead of that monstrosity of an entire shell script:

ltd() {
  if [[ $# -eq 0 ]]; then
    print -u 2 "ltd needs a depth argument"
    return 1
  fi
  local depth=$1
  shift
  lscolor --tree=$depth "$@"
}

then ltd 5 blah blah blah will use the first argument as the argument to that --tree option, and pass the rest through unchanged.

I found the answer during my time putting this question together. The answer comes from here

with the code

#!/bin/sh
# POSIX

die() {
    printf '%s\n' "$1" >&2
    exit 1
}

# Initialize all the option variables.
# This ensures we are not contaminated by variables from the environment.
file=
verbose=0

while :; do
    case $1 in
        -h|-\?|--help)
            show_help    # Display a usage synopsis.
            exit
            ;;
        -f|--file)       # Takes an option argument; ensure it has been specified.
            if [ "$2" ]; then
                file=$2
                shift
            else
                die 'ERROR: "--file" requires a non-empty option argument.'
            fi
            ;;
        --file=?*)
            file=${1#*=} # Delete everything up to "=" and assign the remainder.
            ;;
        --file=)         # Handle the case of an empty --file=
            die 'ERROR: "--file" requires a non-empty option argument.'
            ;;
        -v|--verbose)
            verbose=$((verbose + 1))  # Each -v adds 1 to verbosity.
            ;;
        --)              # End of all options.
            shift
            break
            ;;
        -?*)
            printf 'WARN: Unknown option (ignored): %s\n' "$1" >&2
            ;;
        *)               # Default case: No more options, so break out of the loop.
            break
    esac

    shift
done

# if --file was provided, open it for writing, else duplicate stdout
if [ "$file" ]; then
    exec 3> "$file"
else
    exec 3>&1
fi

colorls --tree=$1

and the alias in .zshrc

alias ltd="zsh ~/ltd.sh"