ZSH: Call in-built function from zsh function that uses the same name

Question

I use zsh and would like to slightly extend the in-built cd function. I'd like that when I call cd, it changes directly and then lists the content of the directory.

function cd() {
    cd $1
    ls .
}

I'd have expected this code to work, but as it turns out, the call to cd refers to the function definition, resulting in an infinite loop.

Is there a work-around to solve this problem, apart from choosing a different name for my function?

UPDATE

Strangely enough, this worked

function cd() {
    `echo $1`
    ls .
}

No idea why.

Answer 1

In order to use builtin commands from within functions of the same name, or anywhere else for that matter, you can use the builtin precommand modifier:

function cd() {
    builtin cd $1
    ls .
}

builtin COMMAND tells zsh to use the builtin with the name COMMAND instead of a alias, function or external command of the same name. If such a builtin does not exist an error message will be printed.

---

For cases where you want to use an external command instead of an alias, builtin or function of the same name, you can use the command precommand modifier. For example:

command echo foobar

This will use the binary echo (most likely /bin/echo) instead of zsh's builtin echo.

---

Unlike with functions builtin and command are usually not necessary with aliases to prevent recursions. While it is possible to use an alias in an alias definition

% alias xx="echo x:"
% alias yy="xx y:"
% yy foobar
y: x: foobar

each alias name will only expanded once. On the second occurence the alias will not be expanded and a function, builtin or external command will be used.

% alias echo="echo echo:"
% echo foobar
echo: foobar
% alias xx="yy x:"
% alias yy="xx y:"
% xx foobar
zsh: command not found: xx

Of course, you can still use builtin or command in aliases, if you want to prevent the use of another alias, or if you want to use a builtin or external command specifically. For example:

alias echo="command echo"

With this the binary echo will be used instead of the builtin.

Answer 2

Why the echo command works is because you probably have the autocd option on. You can check this by typing setopt to get your list of options.

Then the echo-ing of the directory name and catching the output triggered the autocd and you went to that directory.