[ESS] Indentation questions

[Ista Zahn]

Hi all,

I've been unhappy with ESS indention for some time, and finally got
around to trying to adjust it to my taste. It didn't go well, and so
I'm turning to the collective wisdom of this list for help. NOTE: this is
a long post, due mostly to my inability to state my issue clearly. A shorter
version is at https://github.com/emacs-ess/ESS/issues/120

OK, here goes; basically I like how Rstudio
indents things, which mostly means lining up things up by reference to
the calling function. Here are some examples (these examples also
available at http://pastebin.com/y7UERhv6 in case your email client
doesn't like to use a fixed-width font):

#Rstudio:
mean(rnorm(100,
           mean = runif(1,
                        1,
                        10)),
     na.rm=TRUE
)

# ESS
mean(rnorm(100,
           mean = runif(1,
               1,
               10)),
     na.rm=TRUE
     )

The Rstudio version makes it easy to see which lines are arguments to
which functions, and I'd like to set ESS to use a similar indentation
style. I've fiddled with all the ess.*offset variables I can find, but
I can't seem to find a satisfactory setting.

The biggest annoyance is the indentation of continuation lines. There
have been several posts about this including
http://emacs.1067599.n5.nabble.com/indentation-of-ggplot-code-and-ess-13-09-02-td322315.html
which suggests the following setting:

(add-to-list 'ess-style-alist
             '(my-style
               (ess-indent-level . 4)
               (ess-first-continued-statement-offset . 2)
               (ess-continued-statement-offset . 0)
               (ess-brace-offset . -4)
               (ess-expression-offset . 4)
               (ess-else-offset . 0)
               (ess-close-brace-offset . 0)
               (ess-brace-imaginary-offset . 0)
               (ess-continued-brace-offset . 0)
               (ess-arg-function-offset . 4)
               (ess-arg-function-offset-new-line . '(4))
               ))


This does improve simple examples such as turning this:

1 +
    2 +
        3 +
            4

into

1 +
  2 +
  3 +
  4

though I would really like

1 +
2 +
3 +
4

But it still leave more complicated things like

mean(rnorm(100)) +
  2 +
  mean(rnorm(100,
             mean = runif(1, 1, 10)), na.rm=TRUE) +
               2 +
               2

I really don't understand why it makes sense to indent the "2's"
differently depending on whether they come before or after the second
"mean(rnorm(...". Compare this to the Rstudio indentation:

mean(rnorm(100)) +
  2 +
  mean(rnorm(100,
             mean = runif(1, 1, 10)), na.rm=TRUE) +
  2 +
  2

Right. So I hate to be that guy, but seriously, how can I make ESS
indentation behave more like Rstudio?

Thanks,
Ista