oh-my-zsh/plugins/textmate/textmate.plugin.zsh

# If the tm command is called without an argument, open TextMate in the current directory
# If tm is passed a directory, cd to it and open it in TextMate
# If tm is passed anything else (i.e., a list of files and/or options), pass them all along
#    This allows easy opening of multiple files.
function tm() {
	if [[ -z $1 ]]; then
		mate .
	elif [[ -d $1 ]]; then
		mate $1
		cd $1
	else
		mate "$@"
	fi
}