Stop 2nd TAB from undoing indenting

Question

I noticed something that might be a feature, but I find it rather annoying. Say I have a piece of code:

some_function = (x, y) ->
  z()

and I wish to add a new function call one indentation level deeper than the z(). To illustrate it I will use indenting.

some_function = (x, y) ->
  z()
foo()

This is with no indentation

some_function = (x, y) ->
  z()
->foo()

Pressing tab once, places two spaces in front of foo()

some_function = (x, y) ->
  z()
foo()

Pressing tab again does not do the expected behavior of adding two additional spaces. Instead, it de-indents back to the beginning.

Is there a way to override this?

EDIT:

Here's my relevant configuration stuff

(custom-set-variables
   '(coffee-tab-width 2)
   '(coffee-indent-like-python t)
)


(setq-default indent-tabs-mode nil)
(setq-default tab-width 2)
(setq tab-always-indent t)
(electric-indent-mode 1)

Answer 1

From what I have seen with the languages that I work in, emacs major modes for programming languages will often define their own functions to indent code properly for that language. To see some of these functions you can do C-h f type coffee-indent- and then tab to see the list of different indentation functions that coffee-mode provides, and pick one to read it's documentation. I looked through the source code of coffee-mode.el and I don't really understand enough elisp to comment on exactly how what setting coffee-indent-like-python-mode to t will do exactly, but my assumtion from the variable name and from the behaviour it achieves as described in my tests below, is that it causes the coffee-mode indentation commands to behave like python-mode indentation commands (i.e., causes them to behave exactly as you are describing above).

From tests that I ran in a few scratch buffers, I think that the problem is indeed caused by the variable coffee-indent-like-python-mode. Here are the steps that I took to reproduce and then fix your problem (at least in my version of emacs). (Also note that my tabs are bigger than yours, but that shouldn't make a difference. I have enabled whitespace-mode for these screenshots so that it is clear that each indent is a single tab)

1. Opened a scratch buffer and set it to coffee-mode with M-x coffee-mode.

2. Pasted in this code with z() and foo() at the same indentation level:

3. Hit tab on the line with z() indenting it on level

4. Hit tab on the line with foo() indenting it to the same level as z()

5. Hit tab again on the line with foo() nesting it one level below z()

If I understand your question correctly, this is the behaviour you are looking for, right? Pressing tab again on the line with foo() will bring it back to to the first level, subsiquent tabs will cycle through levels one, two, and three in this case.

6. I opened a new scratch buffer in lisp-interaction-mode, entered the code (setq coffee-indent-like-python-mode t) (notice the mode at the end of the variable name which is missing from your sample configuration), and evaluated that code with the point after the last paren with C-x C-e. Then I returned to my coffee-mode buffer and tried indenting again with tab. As expected it indents "like python-mode", i.e., it will not indent foo() past z(), because this kind of indentation is invalid in Python.

7. I went back to my lisp buffer, changed the t to nil, i.e., (setq coffee-indent-like-python-mode nil), evaluated that, and back in my coffee-mode buffer I can indent foo() past z() again.

Please try these experiments, or simply try removing the reference to coffee-indent-like-python-mode in your config (or set it to nil) to see if it works. Let me know if you have other questions or need to do more troubleshooting.