Hello Karl,
> new proposal is to use octal escapes \ooo (and
> nothing else). Specifically:
>
> 1) if the first character of the source is a ", the source name extends
> to the next ". (Including :'s, for example.)
> 2) within that "...", \ooo is recognized. For instance, \042=" and \134=\,
> so this weird filename (5 chars):
> a:"\b
> would be output in an error message as:
> "a:\042\134b":10:some message
>
> This should be about as easy to parse as it can be, and it follows rms's
> "one character one specification" rule.
>
> The \ooo convention could be used for any character, but in an 8-bit
> clean environment, I believe it is only *required* for " and \.
1) For which filenames should the escaped syntax be used and for which not?
From the syntax you gave, and assuming a program that parses line by line,
it is *required* only if the filename
- contains a ':' or newline, or
- starts with a '"'.
Is that the intent?
Or is the intent that it be used for a wider class of frequently used
filenames, such as
- filenames that contain non-ASCII characters? (I hope not, this would
punish people who use their native script for filenames.)
- filenames that contain a space? (I hope not, since these are very
frequent.)
2) Native Windows filenames (which occur in mingw ports of GNU programs)
often contain a colon and backslashes: 'C:\SUBDIR\0049\FOOBAR.PNG'
It would be useful, in my opinion, to use a syntax that preserves the
human-readability and copy&paste-ability of such filenames.
I.e. I would like to see above filename being escaped as
"C:\SUBDIR\0049\FOOBAR.PNG". But this is incompatible with the use
of \nnn as escape sequence.
Since the use of % in filenames is less frequent than the backslash
(on Windows), and since there is already an RFC standard for how to
escape URIs (<http://www.ietf.org/rfc/rfc2396.txt>), I would vote
for using the %nn syntax.
So my proposal is:
- For parsing:
- If the first character is a '"', then the escaped syntax is
in use. The filename is enclosed in "..."; inside,
- occurrences of '"' and '%' are escaped as %22 and %25,
respectively,
- other ASCII characters may be escaped in %nn syntax as well,
where nn is the hexadecimal notation (case insignificant)
of the byte value in the ASCII encoding.
- Otherwise, the filename ends at the first ':' or end of line.
- For output:
The escaped syntax is required if the filename contains a ':' or
newline, or starts with a '"'. It may also be used for other
filenames.
Bruno
