[ESS] elisp problems (was Re: feature request: look more places for R on windows [code])
ross at biostat.ucsf.edu
Thu Apr 18 21:12:12 CEST 2013
I tried using my macro on an XP machine and it didn't work. There were
2 problems, one of which I need help solving.
On 3/28/2013 1:51 PM, Ross Boylan wrote:
> (defun installPath-reg-read (regpath)
> ;read a path in the Windows registry. This probably works for string
> ;values only. If the path does not exist, it returns nil.
> ;Adapted from source:
> (let ((reg.exe (concat (getenv "windir") "\\system32\\reg.exe"))
> tokens last-token)
> (setq reg-value (shell-command-to-string (concat reg.exe " query "
> regpath " /v InstallPath"))
> tokens (split-string reg-value nil t)
> last-token (nth (1- (length tokens)) tokens))
> (and (not (string= last-token "value.")) last-token)))
The first problem is that on XP failure to find a value produces a
string ending in "value" without a period. I added a test for that.
The second problem, which is not XP-specific, is that last-token is not
the right value if there are spaces in the path.
I tried extracting everything after REG_SZ, but I keep getting the
whitespace before the string I'm interested in. Sample attempt
(string-match "^.*REG_SZ *\\([^ ].*\\) *" tlong)
(match-string 1 tlong)
where tlong is my temporary variable corresponding to reg-value above.
I've also tried [:space:].
I either fail to match or get a match that includes a bunch of leading
white-space, perhaps a tab.
Any suggestions how to fix this? Maybe if I looked at the character
codes in the string it would help, but the characters visually are
whitespace, and so I don't know that the problem is. My understanding
is that a space in a regular expression will match at least a space or
a tab (emacs 24.3.1).
tlong is multi-line, if that matters. The fact that it's the result of
shell-command-to-string may be more important in making it behave oddly.
P.S. The code with tlong is typed manually and so might have a
transcription error, though I don't see one.
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