race condition in starting mmm-mode?

[stephe-ada-guru]

(aside; just started using mmm-mode, and so far it works fine, except for this issue)

I'm writing wisi-grammar-mode, a mode for wisi grammar files; similar to bison/yacc grammar files; they have embedded code in elisp or Ada in the grammar actions. To get proper indentation in the grammar actions, I'm using mmm-mode.

It works fine interactively, but fails in my tests. To run a test, I spawn a new emacs, load a wisi-grammar file, run indent, save the result. Then a makefile diffs the test result with the original.

I saw issue #80 about -batch mode; I'm using emacs -Q, so that's not the issue.

To start mmm normally, I've set:
(setq mmm-global-mode 'classes)
(add-to-list 'mmm-mode-ext-classes-alist '(wisi-grammar-mode nil wisi-action))

That relies on post-command-hook to start mmm-mode, which means it runs after the test function, which is the first command run in the spawned emacs. So in the test code, I set:
(add-hook 'wisi-grammar-mode-hook 'mmm-mode-on)

That sets indent-line-function, and an overlay, but the indent is still wrong, so something is still not being set properly.

[stephe-ada-guru]

I figured out the cause of the problem; my test uses 'indent-region', and wisi-grammar-mode provides 'indent-region-function', but mmm only provides 'indent-line-function'. My indent-region sends the buffer contents to an external process that computes the indent.

It might make sense for a new mmm-indent-region to call the appropriate indent-region on each subregion. I'll give that a try.

[dgutov]

Makes sense. One tricky part is to properly delineate regions like this (e.g. skip the ones that don't include a newline, for instance).