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Re: Strange string-append and string-match behaviour
From: |
Andy Wingo |
Subject: |
Re: Strange string-append and string-match behaviour |
Date: |
Sun, 27 Feb 2011 23:27:39 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/23.2 (gnu/linux) |
Hi Francis,
The (most unfortunately indicated!) error is actually a read error due
to malformed input and not related to any of these procedures.
On Fri 18 Feb 2011 05:11, Francis Southern <address@hidden> writes:
> scheme@(guile-user)> (string-match "?.*" "?wobble")
> ERROR: In procedure make-regexp:
> ERROR: In procedure make-regexp: Error while printing exception.
Heh. Fixed this error message to at least not print an exception:
ERROR: In procedure make-regexp:
ERROR: In procedure make-regexp: Invalid preceding regular expression
Still not very good, but it's what libc gives us.
> scheme@(guile-user)> (string-match "\?.*" "?wobble")
> While reading expression:
> ERROR: In procedure scm_lreadr: standard input:3:18: illegal character
> in escape sequence: #\?
OK! At this point "\? was read. It was determined that ? was an invalid
escape char, so the read was aborted. Unfortunately we were inside a
string. What's left is .*" "?wobble", and thus the following errors:
> ;;; <unknown-location>: warning: possibly unbound variable `.*'
> ERROR: In procedure #<procedure 2183020 ()>:
> ERROR: In procedure module-lookup: Unbound variable: .*
Because we read the symbol `.*'.
> $1 = " "
Because we read the string " ".
> ;;; <unknown-location>: warning: possibly unbound variable `?wobble'
> ERROR: In procedure #<procedure 21ac020 ()>:
> ERROR: In procedure module-lookup: Unbound variable: ?wobble
Because we read ?wobble.
> And then it just hung and I needed to C-c C-c my way out.
Because we're inside a string, waiting for the ending ".
Ironically you could have ended it with a \? ;-)
I think the right thing to do here at the REPL is to flush all pending
input when a read error occurs. I have pushed a patch to do that, I
believe. Thanks for the report :)
Andy
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